i have been renaming my forged weapons after legendary weapons in previous games but only Blazing Sword so far, such as aversa's night - Ereshkigal, Katarina's bolt - Aureola and my two brave swords being Durandal and Regal Blade
Back on topic, I don't usually take the time to name mine, but I do have a penchant for all things mythological so I'll sometimes name them after various gods from varied cultures.(Ares, Jupiter, Horus, etc.)
Official Horus of the Shin Megami Tensei IV board Official Walhart and husband of (F)Morgan of FE:A
Well, I have my MU a Blessed Lance because Noire has a Blessed Bow in her portrait, and it seemed fitting. Then one day in a flight of fancy, I went to the forge, maxed its Mt, and renamed it "DivineBuster". I'm not sure why.
Besides that, I gave Valflame to my Arvis. And I know it doesn't actually make sense, but I also gave my Deirdre a Book of Naga..
Official Bride and Wife of Noire (of the Fire Emblem Awakening message board)