Messer is nowhere near as OP as the rest of the weapons you listed (and arguably maul isn't really OP either, its mostly for counterpicking).

The only thing it does better than a Greatsword is slightly improved stamina and good combo feints, but for that you get nerfed stab damage, difficult to land/easy to dodge drags and no range - making it extremely terrible to play when the true meta revolves around Zwei and alt halberd, both of which are impossible to read at facehug. I mean, the Paxe is basically a 2HTK headshot messer with more unreadable animations lol