There are 4 types of dragon artifacts.
1. Bleed charm.
It causes moderate bleeding damage overtime, with a 5% increase for every enemy you hit, capping at around 50%.
2.Attack power up charm
For every enemy you hit it increases your total damage by 10%, capping at a 100% attck boost, basically doubling your damage.
3.Defense power up charm
Increases your defense the same way as the attack power up charm.
4.Speed charm.
Speed charms increase (max capping at) 50% attack, buster generation and movement speed.