Hammer of the singing forge
This hammer reads +100% attack and +1 metal.
I think in the game i am playing i am gaining a permanent +1 to my metal per turn every time i use this in a battle - at the moment i have only needed to use it once per fight but i am about to try using it as the only weapon used during a battle and will keep my army back to see what happens.
It appears from the text that it should be +100% attack, i would assume a cooldown period, and +1 metal per turn. Not per use in a battle permanent bonus.
Ay caramba.