"This shield I noticed chipped after I used it against a fire mana attack with earth mana mixed in. It made a wave of lava move toward it, so when I looked deeper I found out there might be an impurity in the metals. I don't think it was from the crafting, but the finishing afterwards. The sealing liquid used might have been impure and you or I didn't notice at the time."
Su has been showing off the smallest of small chips in a shield made for resisting heat and fire mana specifically. She had noticed the chip because she had cared for her shields and armor sets carefully. That was her duty to remain as a proper protector of anyone.
The reason the seal chip smaller than a fingernail was so worrisome to her was because that chip could cause the entire shield to break.
