Holosmith (5e Feat)
From D&D Wiki
Prerequisites: You must be a Bismuth of the Gem race.
Using a forge and smith’s tools, you are capable of creating attachments that fit onto Gem armaments created by Gems. This takes 2d4 days to complete and requires the presence of the Gem whose armament you are modifying. Once complete, their armament increases attack and damage rolls by 2 if it is a weapon, or AC by 2 if it is a shield or armor piece. This can only be performed once per Gem.