Yes, Durengal is a sword that was turned into a woman by Castir. It's a very NSFW origin. The series also seems to establish that Castir gained a crush on her.

Imagine how awkward that'd be; You're a sword that was turned into a human by a wizard, and now they're falling in love with you.

I would NOT want to be in that situation...

Trivia: Durengal's name is a portmanteau of 'gal' and 'Durendal', the name of a sword wielded by the fictional French paladin, Roland!

Link for more info: https://en.wikipedia.org/wiki/Durendal