No idea, but there is no satisfying boom, the thing fractures, IIRC, and it is useful against at most 1 target.
Literally the Ogryn's change does more damage.
Even the Zealot/Preacher's grenade is more useful, but that is wonky too.
And don't get me started on annoyances I have with weapons switching on ability usage...
Also, I haven't died/been taken captive once, and got him up to lvl 11 with comparative ease.
I will be testing out the shield and club combo as soon as I have a few hours for gaming.
Also, I had some lower level dude trying to boss the whole party earlier today, wtf!!!