In the port that I'm doing, Toughness powers are rather different. Stress boxes are easier to come by. Again, it's based on D&D.
My reasoning with shields: I dislike the idea that a shield could be a single piece of equipment that does everything. That is, defend against anything, attack, and provide armor. Hence the penalty to defense if you attack with it. There's a stunt that prevents this.
I did consider other rules. Specifically:
Flails ignore armor bonus from shields.
Swords provide +1 bonus to defense rolls.
Hammers and picks ignore mundane Armor (but not from shields) equal to Weapon rating.
Axes inflict consequences one step higher.
On a successful attack, maces and clubs place “Battered” aspect of Weapon rating strength vs. Endurance.
Polearms block opponents’ movement equal to Weapon rating on a successful attack.
Whips gain +2 on maneuvers.
Daggers gain +1 on attacks. This stacks with the Weapon Focus talent.
This may be taken multiple times, but must apply to a different weapon group each time.
These have become stunts.
On Weapon values increasing: I want mundane characters to be on par with spellcasters. Spellcasting is easier and doesn't have Laws restricting it. Since mental stress is more common, it's even more potent. Stronger weapon values aids in this.