This short guide explains how you can get the last mace in the Infernax game. Warning! There might be spoilers.
How to Get the Last Mace
The last mace can only be obtained as part of the good ending. You need to do enough good deeds until you get a quest in Kastski to go to Darsov, talk to Tancred, and get reinforcements.
Then you follow the questline until the door opens to the Nightmare Cathedral, which is behind breaking walls and a switch in the cemetery area.
Then you’ll get the Necronomicon. The final mace is your reward for clearing the crypt that you access by breaking the right-most wall in this room.
You should be able to do 1 “wrong” choice and still get the ultimate good/bad ending. So just make sure you have found all of the options. There is the 1 little hut at the start of the game that is only open on day that has one quest that is easy to miss.