That changes things considerably. Consider the nature of the monster and its culture. If it's savage, something like 'Smasher' or 'Basher', as suggested above is certainly evocative. If it's more civilized, come up with some pretentious name for it based on what they call their units.
Just saying that in this instance I'd base this not on what we'd call a mace-wielder, but rather what they call their mace-wielders.
Why would you mace-represent an entire group like that? Clearly you are betraying your own macist tendencies here. Something is definitely a-mace here.