How viable is the Terraprism in endgame?

So I got really lucky and had a legendary Terraprism blueprint drop from my second Terria dungeon run, and while it is interesting, it seems to be doing very little damage while I'm running around Feybreak Island. Or at least compared to my pals. I've been running around with a max trust four star 30% soul buffed 75+ IV Mozzarina (cuz funny) and she will basically one-shot any regular pal that looks at me funny, but the flying swords are only dealing 15-20 damage per hit. Yes they hit fast, but there are higher level areas (I assume) so it's only going to get worse.

I do currently have a spare weapon slot, so I'm not really giving up anything to have it around, but if it's only going to deal 1% of a bosses health over the entire 10 minute fight is it really useful?