AMENDMENT TO INSIDER LETTER

THIS AMENDMENT TO INSIDER LETTER (this “Amendment”) is made and entered into as of November 9, 2025, by and among (i) Columbus Acquisition Corp, a Cayman Islands exempted company (together with its successors, “CAC”), (ii) WISeSat.Space Holdings Corp., a British Virgin Islands business company (“Pubco”), (iii) Hercules Capital Management VII Corp, a British Virgin Islands company (the “Sponsor”), (iv) WISeSat.Space Corp., a British Virgin Islands business company (the “Company”) and (v) the undersigned individuals, each of whom is a member of CAC’s board of directors and/or management team and who, along with the Sponsor and other transferees of the applicable CAC securities, is referred to as an “Insider” pursuant to the terms of the Insider Letter. Capitalized terms used but not otherwise defined herein shall have the respective meanings assigned to such terms in the Insider Letter (as defined below) (and if such term is not defined in the Insider Letter, then in the Business Combination Agreement (as defined below)).

RECITALS

WHEREAS, CAC, the Sponsor and the other undersigned Insiders are parties to that certain Insider Letter, dated as of January 22, 2025 (the “Original Agreement” and, as amended by this Amendment, the “Insider Letter”), pursuant to which the Sponsor and the undersigned Insiders each agreed, among other matters, to (i) waive their redemption rights with respect to any Ordinary Shares owned by it, (ii) waive their rights to liquidating distributions from the Trust Account with respect to their Insider Shares and Ordinary Shares underlying the Working Capital Units if CAC fails to complete its initial Business Combination within the completion window, (iii) vote in favor of any proposed Business Combination for which CAC seeks approval, and (iv) certain transfer restrictions with respect to the Insider Shares and Private Units;

WHEREAS, on or about the date hereof, (i) CAC, (ii) Pubco, (iii) the Company, (iv) WISeSat Merger Sub Corp., a Cayman Islands exempted company and a wholly owned subsidiary of Pubco (“Merger Sub”), (v) WISeKey International Holding Ltd., a Swiss company (together with its successors, including after its anticipated domestication to the British Virgin Islands prior to the Closing, the “Seller”) entered into that certain Business Combination Agreement (the “Business Combination Agreement”);

WHEREAS, pursuant to the Business Combination Agreement, subject to the terms and conditions thereof, upon the consummation of the transactions contemplated thereby (the “Closing”), subject to the terms and conditions thereof, among other matters, (a) Pubco will acquire all of the issued and outstanding Company Ordinary Shares and Company Class F Shares from the Seller in exchange for Pubco Class A Ordinary Shares and Pubco Class F Ordinary Shares, such that the Company will become a wholly owned Subsidiary of Pubco and the Seller will become a shareholder of Pubco (the “Share Exchange”), and (b) Merger Sub will merge with and into CAC, with CAC continuing as the surviving entity (the “Merger”), and as a result of which, (i) CAC will become a wholly-owned subsidiary of Pubco, and (ii) each issued and outstanding security of CAC immediately prior to the effective time of the Merger will no longer be outstanding and will automatically be cancelled, in exchange for the right of the holder thereof to receive a substantially equivalent security of Pubco, all upon the terms and subject to the conditions set forth in the Business Combination Agreement and in accordance with the provisions of applicable Law;

WHEREAS, the parties hereto desire to amend the Original Agreement to (i) give Pubco and the Company rights to enforce the terms of the Insider Letter, (ii) effective as of the Closing, assign the rights and obligations of CAC under the Insider Letter to Pubco and (iii) provide that the lock-up period applicable to the Pubco Class A Ordinary Shares issued in exchange for the Founder Shares pursuant to the Business Combination Agreement will be identical to the lock-up period set forth in the Lock-Up Agreement; and

WHEREAS, pursuant to Section 17 of the Original Agreement, the Original Agreement can be amended with the written consent by Sponsor and each Insider.

NOW, THEREFORE, in consideration of the premises and the mutual promises herein made, and in consideration of the representations, warranties and covenants herein contained, and intending to be legally bound hereby, the parties hereto agree as follows:

1.Addition of Pubco and the Company as a Party to the Insider Letter. The parties hereby agree to add each of Pubco and the Company as a party to the Insider Letter. The parties further agree that, from and after the Closing, (i) all of the rights and obligations of CAC under the Insider Letter shall be, and hereby are, assigned and delegated to Pubco as if it were the original “Company” party thereto, and (ii) all references to “the Company” under the Insider Letter relating to periods from and after the Closing shall instead be a reference to Pubco. By executing this Amendment, Pubco hereby agrees to be bound by and subject to all of the terms and conditions of the Insider Letter, as amended by this Amendment, from and after the Closing as if it were the original “Company” party thereto.

2.Amendments to the Insider Letter. The Parties hereby agree to the following amendments to the Insider Letter:

(a)The defined terms in this Amendment, including in the preamble and recitals hereto, and the definitions incorporated by reference from the Business Combination Agreement, are hereby added to the Insider Letter as if they were set forth therein.

(b)The parties hereby agree that from and after the Closing, the terms “Ordinary Shares,” “Insider Shares,” “Private Shares,” “Private Units,” as used in the Insider Letter shall include any and all Pubco Ordinary Shares into which any such securities will convert in the Merger (and any other securities of Pubco or any successor entity issued in consideration of, including as a share split, dividend or distribution, or in exchange for, any of such securities).

(c)Any reference to the term “including” (and with correlative meaning “include”) in the Insider Letter means including without limiting the generality of any description preceding or succeeding such term and shall be deemed in each case to be followed by the words “without limitation”.

(d)Effective upon the Closing, the term “Insider Shares” in Section 5 of the Original Agreement shall be replaced in its entirety with “Founder Shares” (as defined in the Business Combination Agreement). For the avoidance of doubt, the transfer restrictions in Section 5 of the Original Agreement shall not apply to any Pubco Ordinary Shares issued upon conversion of the Private Units (including the Private Shares and Rights underlying such Private Units) and Working Capital Units in connection with the Merger after the Closing.

(e)Effective upon the Closing, Section 5 of the Original Agreement is hereby amended to add the following new subsections (d) and (e):

“(d) If any Transfer is made or attempted contrary to the provisions of this Letter Agreement, such purported Transfer shall be null and void ab initio, and Pubco shall refuse to recognize any such purported transferee of the restricted securities as one of its equity holders for any purpose. In order to enforce this Section 5, Pubco may impose stop-transfer instructions with respect to the restricted securities of each Insider (and any transferees and assigns thereof) until the end of the applicable Lock-up Periods.

(e) During the applicable Lock-up Periods, each certificate or book entry evidencing any restricted securities shall be stamped or otherwise imprinted with a legend in substantially the following form, in addition to any other applicable legends:

“THE SECURITIES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO RESTRICTIONS ON TRANSFER SET FORTH IN A LETTER AGREEMENT, DATED AS OF JANUARY 22, 2025, AS AMENDED ON NOVEMBER 9, 2025, BY AND AMONG THE ISSUER OF SUCH SECURITIES (THE “ISSUER”), THE ISSUER’S SECURITY HOLDERS NAMED THEREIN AND CERTAIN OTHER PARTIES NAMED THEREIN, AS AMENDED. A COPY OF SUCH LETTER AGREEMENT WILL BE FURNISHED WITHOUT CHARGE BY THE ISSUER TO THE HOLDER HEREOF UPON WRITTEN REQUEST.”

3.Effectiveness. Notwithstanding anything to the contrary contained herein, this Amendment shall become effective upon the Closing. In the event that the Business Combination Agreement is terminated in accordance with its terms prior to the Closing, this Amendment and all rights and obligations of the parties hereunder shall automatically terminate and be of no further force or effect.

4.Specific Performance. Each party acknowledges that the rights of each party to consummate the transactions contemplated hereby are unique, recognizes and affirms that in the event of a breach of the Letter Agreement by any party, money damages may be inadequate and the non-breaching parties may have not adequate remedy at law, and agree that irreparable damage would occur in the event that any of the provisions of the Letter Agreement were not performed by an applicable party in accordance with their specific terms or were otherwise breached. Accordingly, each party shall be entitled to seek an injunction or restraining order to prevent breaches of the Letter Agreement and to seek to enforce specifically the terms and provisions hereof, without the requirement to post any bond or other security or to prove that money damages would be inadequate, this being in addition to any other right or remedy to which such party may be entitled under the Letter Agreement, at law or in equity.

5.Miscellaneous. Except as expressly provided in this Amendment, all of the terms and provisions in the Original Agreement are and shall remain in full force and effect, on the terms and subject to the conditions set forth therein. This Amendment does not constitute, directly or by implication, an amendment or waiver of any provision of the Original Agreement, or any other right, remedy, power or privilege of any party thereto, except as expressly set forth herein. Any reference to the Insider Letter in the Original Agreement or any other agreement, document, instrument or certificate entered into or issued in connection therewith shall hereinafter mean the Insider Letter, as amended by this Amendment (or as the Insider Letter may be further amended or modified in accordance with the terms thereof and hereof). The terms of this Amendment shall be governed by, enforced and construed and interpreted in a manner consistent with the provisions of the Original Agreement, including Section 13 thereof.

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IN WITNESS WHEREOF, each party hereto has signed or has caused to be signed by its officer thereunto duly authorized this Amendment to Insider Letter as of the date first above written.

Sincerely,
CAC:
COLUMBUS ACQUISITION CORP
By:	/s/ Fen Zhang
Name:	Fen Zhang
Title:	Chief Executive Officer
Pubco:
WISESAT.SPACE HOLDINGS CORP.
By:	/s/ Carlos Moreira
Name:	Carlos Moreira
Title:	Director
The Company:
WISESAT.SPACE CORP.
By:	/s/ Carlos Moreira
Name:	Carlos Moreira
Title:	Chief Executive Officer
By:	/s/ John O’Hara
Name:	John O’Hara
Title:	Chief Financial Officer

The Insiders:
HERCULES CAPITAL MANAGEMENT VII CORP
By:	/s/ Fen Zhang
Name:	Fen Zhang
Title:	Sole Director
/s/ Fen Zhang
Name:	Fen Zhang
/s/ Jie Hu
Name:	Jie Hu
/s/ Cameron R. Johnson
Name:	Cameron R. Johnson
/s/ Kevin McKenzie
Name:	Kevin McKenzie
/s/ Qian Xu
Name:	Qian Xu