Somewhere, Grombindal had held an Ilithmar cup, a gift from his Best Buddy Malekith and remembers the good times as bros. The symbol of their broken friendship and promise Malekith turned his back on him.Well malekith did make his bestie a cup made of Ilithmar back in the day so i'm sure some noble has all of their cutlery be made of it
Not wanting to do with it anymore, Grombindal gave that cup to some random Umgi he encountered in his path, not caring if the cup would be sold or melt it down for some Umgak stuff, and he never looked back.
Only settling the Grudge against the Witch-King no matter what it takes.
Meanwhile, the random Umgi whom Grombindal gave the cup to was a Cathayan named Shen Zoo in her journey of the West and was enamoured of the cup's Ilithmar, keeping it for herself.