Add different special properties to alloys or metals in order to diversify metals used in the world. This could include of anything that might be considered unique.
Valyan is used all the time and is very hard to counteract if you are on the receiving end. While this is very rewarding to get and grind to, it results in all other metals except gold being used entirely for decoration. This does not have to include unique abilities for every metal, but at least a change of stats to allow for other metals to see the light of day. If you have any ideas for this, comment down below.