Block weapons need to actually block.
I've played about 150 hours of operations and block weapons still feel inferior to fencing/balance. The adrenaline buff is a step in the right direction but in large mobs of enemies it seems too difficult to stack for the damage payoff you get, especially with the thunder hammer.
My idea to make it better without hopefully making it too overpowered is this. Have block weapons block ranged and melee attacks (not orange) while holding a blocking stance. The idea is that you hold the parry button but cant move (like the heavy class strategic stance perk) the timing window is removed and you can hold this stance indefinitely. During the stance any hits (besides orange) would build the adrenaline buff but, if you take a hit with max stacks of adrenaline you get staggered and lose the stacks. I feel like this is similar to the risk/reward with the parrying/gun strike mechanic. additionally it would help with zoanthrope/nuerothrope/enlightened tzaangor counter-play for the more melee focused classes.