No personal armor (so far) is good against blunt trauma. The reason for that is conservation of momentum. Blunt weapons often rely on large amount of momentum. Only thing you can do is to make the armor bouncy. So you can try to turn it into elastic collision.

https://en.wikipedia.org/wiki/Elastic_collision

But then again they often added small spikes and rough surfaces to the tips of such weapons, to turn it into inelastic collision. http://www.medievalcollectibles.com/images/Product/large/AH-... https://en.wikipedia.org/wiki/Inelastic_collision

The bad shit for the weapon is that it's very difficult to change the direction of war-hammer mid course. So it's easier to block.

Kevlar makes armor of similar effectiveness lighter. But there is nothing fundamentally better than old plate armors. It's still just distributing force to larger area. With penetrating weapons this is potentially very effective, as there is relatively little momentum and energy. The idea is to have very high local pressure at the tip of the weapon and this normally cuts deep into flesh.