The higher your magic skill for a given type the higher the number of charges a weapon has for that same type. That is a character with 100 destruction would get more charges out of a flame sword than a character with 10 destruction. So what you want to do is increase the magic skill that corresponds to those artifacts and it will increase the charges available.
Thank you. Not my thread but I did not know this either. Those two said weapons sit on racks and walls in my home for this reason. I'm a sword and board char that specs in 1handed axes.
Gotta love chief O'brian. 1 of my favs across a couple series.