Should it be both better AC than a shield and shareable? That sounds a little strong to me. Cool idea though.
Yay give me some swordmage pleaseWhat about, for a defensive gish style:
Aegis. While wielding a melee weapon in one hand, and a component, arcane focus, or free hand, you gain a +3 bonus to AC. When an ally is the target of an attack while within 5ft of you, you can transfer this benefit to them as a Reaction. You lose the benefit while it affects them, and this effect lasts until the start of your next turn.
Since it costs more, it has to do more. A shield is +2, but costs a fighter essentially nothing. Shield + defensive style is also +3, while Protection and shield is +2 and a stronger protection Reaction.Should it be both better AC than a shield and shareable? That sounds a little strong to me. Cool idea though.
Probably fire, cold, Lightning, Thunder, and Acid.Is that +1 AC designed to be use with a particular loadout or is the idea for it to potentially stack with some of the other styles? If you wanted AC and damage it could also be elemental damage keyed of successful opponents hits, like an aura. That's a lot less sword mage-y though.
+1 AC/+1 TH and changeable damage types doesn't seem over-powered. Is that going to be the full list of damage types, or restricted in some way?