Either you resist the Manablade with Willpower, or you resist the Powerblade with Body, but both versions are pure magical energies and should pass through armor just like the Bolt spells do.
I agree completely about the powerblade that powerblade passing through armor, IF in fact, it is based on powerbolt spells.
We have a Jedi-themed character that just came in to our game and I felt like I had to recast those two spells to make more sense. As written, manabolt seemed a little too strong and powerblade was WAY too weak to be worthwhile for a mage to use. Both weapons have non-trivial drain if you cast them at a force worth having and a mage getting into melee is it's own penalty AND the sustaining thing is another drawback. Then once you get into melee, the manablade was nearly an instant win and powerblade is... meh.
Take it or leave it, but here' is what I did for those two spells:
Drain on both is F-3.
Base damage on manablade weapon is the net hits on the spellcasting.
Powerblade is a physical manipulation spell to account for it being blocked by armor and stuff.
Powerblade still has base damage based on force, but AP = net hits x2.
Both weapons add armed combat net hits to the weapon base damage as normal.
Much of this was based on my players desire to be jedi-like so the powerblade does a little more damage, but it's REALLY good at cutting through barriers and stuff (with enough time of course). So in this version Powerblade is not based on powerbolt except as the idea was spawned from the Manablade research. Manablade is still the ethereal blade described in the book and can be used in astral combat to replace your charisma as your DV.
Since Manabolt is simply spellcasting vs Will = damage, I wanted to keep the same mechanic for this manablade and this tones it down just slightly. Now if you aggregate the rolls, manablade damage ultimately becomes Blades + Spellcasting vs Will + Physcal defense, so it gives the mage 2 opposed dicerolls to do damage at the same time. Better, but with the risks of melee.
One more thing: With powerblade AP being net hits x2, it becomes more on par with manablade for damage since with very high net hits since it will significantly reduce armor on regular dudes, but probably not entirely on corp security with 18+ armor.