Some Magic Weapon/Armour Abilities

[RMS Oceanic]

[Armor/Shield] of Force
Price: +2 bonus
Effect: As an immediate action, you can sacrifice your armor/shield bonus to AC (including any enhancement bonus from these), to gain a force bonus to your touch AC (and only touch AC) equal to the amount sacrificed. This lasts until the end of your next turn.
Special: If you have both a shield and piece of armor with this ability, you can choose to utilise one or both of the abilities as part of the same action.
Caster Requirements: Craft Magic Arms and Armor, Mage Armor

[Weapon] of Nimble Wielding
Price: +1 Bonus
Effect: This weapon can benefit from the Weapon Finesse feat. If it already could, and the wielder has Weapon Finesse, they gain a +1 bonus on attack and damage rolls with this weapon.
Caster Requirements: Craft Magic Arms and Armor, Weapon Finesse, True Strike or Keen Edge

[Weapon] of Mighty Critical
Price: +2 Bonus
Synergy Prerequisites: Keen (Slashing/Piercing weapons) or Impact (Bludgeoning weapons)
Effect: The weapon functions as a keen weapon. In addition, the critical multiplier is raised by one, from x2 to x3, x3 to x4 and x4 to x5. This ability does not stack with any other feat, spell or ability that would increase the critical multiplier. This ability has no effect on creatures immune to critical hits.
Caster Requirements: Craft Magic Arms and Armor, True Strike, Keen Edge

What do you think?

[Triaxx]

I like them all, though shouldn't an armor of force also negate force damage?

And is a Weapon of Mighty Critical affected by Keen, or other threat range increasing enhancements?

[keyboardboy101]

I like all of these, but why does a weapon of Might Critical have the synergy prerequisites? It seems like it could probably just be a standalone enhancement. Just wondering about a justification, not criticizing.