Most might think he's very arrogant, however I think it's just his personality. I don't remember what chapter it was or what was happening at that time, but Hua Cheng face was mischievous but E-Ming in his grasp was tight. That meant he didn't underestimate his opponent.
When someone has arrogance, it means their head is filled with high false perception of themself. Hua Cheng is just confident in his abilities and it's true.