Copper wepons have a 10% chance to channel lightning

When wearing Copper armor, players should have an increased chance of being struck by lightning regardless of weather, and accumulate charge.

Charge alongside durability should do a few things. Firstly for an amount of charge, players should be able to release lightning with tools. Armor should be the (battery) and could be charged on a armor stand with a lightning rod overhead. Or in copper chests with Redstone ( ex redstone batteries that could lose signal strength over time)

if this feels to overpowered then the player can take damage on lightning strikes unless they have the grounding enchantment on boots or wear leather boots. Chanelling should also be used on armor to increase charging speed and chance to be struck by lightning. While on tools it should increase lightning damage.

If charge is not used, it should increase attack speed and efficiency the more charge accumulateted. If an armor peice is broken, the max storage for charge should be reduced( 25% per copper armor peice.)

An iron trim could add a slight armor bonus to copper.