This is one of the things that bugged me about this game. In every other DMC game, the weapons were actual Devil Arms; they had demons inside of them. In DMC3 in particular, the weapons you used WERE the bosses you fought and defeated. It gave them a hellova lot more character.
In this one? It's like "Oh look, Dante's got an axe. It's demonic! How do you know? It's red. And over here? This one's a scythe! It's blue, cause, you know, it's angelic. We put a lot of thought into these designs, guys."
It's particularly aggravating for the ones you get for beating the Succubus/Barbas. Like it would've been so easy for them just to make the designs more based around the enemies you fought... But they just didn't.
Same goes for having enemies/bosses with actual mythological backgrounds, giving Mundus any sort of characterization that wasn't facepalm worthy, using Nelo Angelo instead of "Hollow Vergil", including, you know, a lock-on feature, having Vergil actually betray Dante instead of just arguing...