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 copper 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 too 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.) 

In addition to the copper, alloys should also be introduced. With the armor trim system, armor should gain slight bonuses for using certain materials for trims : ex iron gives more armor points to copper. 

(though not urgent gold, diamond, amethyst, ect can be used for special addon bonuses. Like armor toughness or knockback. Increasing the players individual customization choices.

A simpler way to do it would just be to give copper wepons a 10% of lightning but that's not as intriguing.