In what sense do you mean "honor someone"?
The word honoraria is used to convey gifts or payments made in this sense:
a payment in recognition of acts or professional services for which custom or propriety forbids a price to be set
However, if you actually mean that you are giving a gift in their honor, then "honorary gift" is a perfectly acceptable term. See, for example, the Metropolitan Opera's page on Memory & Honorary Gifts, or the results from this search term.