In DireWolf20 1.21, version: relics-1.21-0.9.0.1

Used shadow glaive ability Merciless punishment.
Big spinning blade stuck in the world and never returns. Stops dealing damage to enemies, and wont let charges of the relic recharge.
May have been caused by moving glaive off hot-bar, changing location, putting it in a bag, or getting stuck after hitting too many enemies.

In the one of latest updates Shadow Glaive was reworked, so it's not an issue anymore I think