You cant use Alchemy fire on a maul.
It's known. You cannot use anything on them if you target through inventory. I simply have not had time to sort it out. It'll come when I have time to look into it, possibly. I am not certain if it'll work at all.
I had a feeling you knew about it, but I thought I better report it anyway. Good work on the costum weapons anyway. Keep up the good work :)