Is its piss-poor range, which seriously hinders its use in PvP and can be an issue in PvE. Much of the Omnigul strike (especially in a Nightfall) is either outside of its range or you want to be rocking a shotty or rocket launcher.

But we might find that a 365 Fatebringer is actually able to overcome some of those range issues in PvE.

In PvP, it has great impact (up there with Hawkmoon, I think), but no Send It to let you leverage that. That said, they might let folks reforge any weapon some day.