Zote is a traveller from outside Hallownest who came to the Kingdom to fulfill a promise. This is ultimately revealed to be a promise of glory for himself.

He named his nail "Life Ender" because names supposedly have power. Unfortunately, because it is made of shellwood, it cannot deal damage.

While he claims to be the strongest warrior in the land, he is found trapped by weak enemies or claiming the glory of another bug's deeds. He regards the Knight as beneath him and accuses them of constantly getting in his way.

More facts here: https://hollowknight.fandom.com/wiki/Zote