I had to use a bomb as well. Eldritch Blast does 1d10 + Cha and 2H sword does 2d6 + Str, so if you get lucky you might do over 10 damage but you have to hit over and over and over and over and over doing no damage at all except when you occasional roll over 10 damage. It has nothing to do with damage type. Bludgeoning vs piercing for example doesn't matter. You have to roll over 10 damage.