See the issue I reported to Better Combat here:
ZsoltMolnarrr/BetterCombat#472

If the player is holding the Soulrender in their primary hand and any non-weapon item in their offhand, no attacks will be considered valid and the client will crash.

I submitted the issue to Better Combat as I feel they should probably handle this more gracefully than crashing.

Still, it seems like the Soulrender's weapon attributes probably need another look; not sure what the intent is for them.

This is fixed in the latest release 🙂

Thanks for the report, Muon!
I'm aware of this one and forgot to fix it in the last update. I'll resolve it next update 🙂