[quote=@MelonHead]
<Snipped quote by GreivousKhan>

Having armour impervious to anything but a charged attack is a huge advantage, as it does not require any charging or thought at all to work, it essentially gives you a save for any mistake you make while not requiring you to sacrifice anything as it's basically weightless. 
[/quote]My punches would have only negligible problems to harm him, actually.
Also your analogy to 25 inches of steel is kinda wrong.
Impact mechanics are more complex than that.
Even if it's indeed 50 times tougher than Kevlar and can dissipate some of the force the airy thin material won't be any help against an .50cal BMG shot for example.
And your piercing attacks wouldn't be any weaker than that, I suppose.