Maces haven't been uncommon in Villages in my playthroughs, but for some reason they don't spawn inside the buildings, they actually spawn outside on the ground, on top of a stone. I've seen them in Kaumo, Reemi, Kiesse and Driik, so I don't think they're specific to one type of culture.
Just keep an eye out when you walk around a village; if you see what looks like a club on the ground, it's always often a mace. It can spawn a fine or masterwork mace as usual, but maces just have that specific spawn quirk. I think the justification as to why they spawn outside is that the mace & stone are supposed to emulate the club & flat surface that the player needs to tan hides.