Grief Runeword

Grief is the best melee Runeword without a doubt. The main reason why Grief outclasses all other weapons is because of its flat damage boost. This damage boost is not visible in the character screen or on the weapon itself, so your damage wll be much higher in reality. This allows you to make Grief in a very fast but low damage weapon, like a phase blade. This damage boost is also one of the only modifiers that work with a Paladin's Smite attack.

On top of that, it provides a significant boost to increased attack speed, makes you ignore target's defenses and has 20% chance of deadly strike. Besides all its overpowering abilities, it's not even super expensive, with the highest and only high rune required being the Lo rune. This puts Grief in the top 1 spot of Overpowered Runewords.