Pierce charms give extra pierce to the user for one single attack, but right now they're pretty useless at only 10%. New and improved spears: Firespear :+15% to next spell Icespear :+15% to next spell Stormspear :+15% to next spell Lifespear :+15% to next spell Mythspear :+15% to next spell Deathspear : +15% to next spell Balancespear : +10% to next spell
Hopefully KI well let us enchant these to make them more efficient.
I think that the 10% pierce is fine. First, we have strike which gives + 50% pierce. We also have school bubbles that range from 15-17 all the way up to 25% ish pierce + Infallible.
Which totals out to 100% pierce (If your bubble does 25%).
Not even talking into consideration that most level 100 wizards have around 10-20+ base pierce from their gear.
to next 
Icespear :+15%
Stormspear :+15%
Lifespear :+15%
Mythspear :+15%
Deathspear : +15%
Balancespear : +10%