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.

So morning star would be the weapon of choice there I suppose. Sword may win "by points" but with morning star you'd have a solid chance of actually neutralizing opponent.

Historically, the weapon of choice for defeating plate armour was the pollaxe.

- https://en.wikipedia.org/wiki/Pollaxe - Fiore's azza: http://scholasaintgeorge.org/training_docs/Basic%20Poleaxe%2...

Flanged mace should be pretty decent too: https://en.wikipedia.org/wiki/Mace_(weapon)#European_Middle_...

historic plate, chain and other armors (including helmets) had significant padding, layers of it, underneath. This both stops arrows, spikes from reaching the skin and cushions spreads impact out.

Impact weapons were rare when hvy armors were in use. OTOH, heavy chopping polearms/swords (to get through joints in armor), and anything to knock plate wearer on ground (to then poke them in between armored bits) were developed and become more popular as heavier armors came about.

> Impact weapons were rare when hvy armors were in use

No they weren't. Cheap and cheerful mauls and war hammers were very popular on mediaeval battlefields - the archers at Agincourt used them as secondary weapons against knights for instance.

And of course it is easy to turn a two-handed sword into an impact weapon as well - turn it around and use a pommel strike.

Really nice article here, btw: http://www.metmuseum.org/toah/hd/aams/hd_aams.htm