The man had two children with the widow, and a number of children from previous marriages.
The widow failed to pay the lawyer and instructed a new lawyer on the case in 2013.
The tribunal found the lawyer committed professional misconduct when he was instructed to transfer all the funds in the term deposit to a new account held by the new lawyer. He deducted more than $10,000 from the account, before transferring the rest of the funds.
The lawyer's counsel told the tribunal he took the money "after trying tirelessly to resolve the matter and the metaphorical 'slap in the face"', referring to the new lawyer being instructed.
The tribunal said the lawyer knew that the money was not available to be taken to pay his fees and his conduct was unsatisfactory.
The standards committee said the lawyer had misled the trust that was appointed executor of his will by not clearing up a misinterpretation that the term deposit was in the name of the husband and wife. The tribunal said this wasn't negligent and didn't amount to misconduct.
The committee also alleged the lawyer had misled Westpac bank into releasing the funds to the widow. The tribunal said the documents he prepared were neither misleading or deceptive and threw out the charge.
The lawyer was ordered to pay $10,000 towards the costs of the Law Society and was ordered to make a refund of the costs of the tribunal not to exceed $8000.