The rules are impossible honestly.

Some bronze upgrades you need iron stuff for to upgrade the forge.

Same with leather/troll stuff... you need the bronze to upgrade the crafting station to fully max those things.

And what does "Odin's favor" actually mean and how does anything stack when you kill a boss? I don't even understand what you are doing here. Is that from some mod? I play vanilla so I have no clue what you are talking about.