You watched as Childe aggressively sharpened his knives and swords.

Some of his spears lay on the floor in a pile, and some (the ones that costed a lot or ones that were gifts from loved ones) were resting against the wall.

He always did this when he was upset, or he lost a fight.

and you learned this a few weeks into your relationship as lovers when you walked home and found out he lost a spar, and there was just the metallic dust on his hands.