It is more or less the dwarf equivalent of the SnD but it trades mobility and DPS for some extra upfront fighting power via stagger and cleave if i am not mistaken. So the weakness is getting bogged down in melee with multiple elites that keep forcing the user to dodge/block.
Monsters can also get very problematic on it due to the lower mobility…but either is mostly a weakness that wont get hit honestly. But on that note its worth considering that all characters have a weapon or even two(career boosted/elf) like that.
That and maybe a bit of superarmor damage, it hit me that it´s probably too effective there.