Bubbles of evil have and wierdness in the pattern have so far been localised events such as people sinking into the ground in front of Mat while the streets elsewhere are ok. So most likely metal elsewhere is ok.

If the adam did melt it would cause problems to the Seanchan but a particularly well trained damane would probably look for directions from her sul'dam even without the collar. Others would run or get very confused but some have been broken to the degree that they want to obey.