
There's no reason to put your main weapon as a defending weapon, really.
Seeing as how you can get +1 defending armor spikes, +1 defending shield spikes, +1 defending gauntlets, +1 defending braid blade, +1 defending dueling cloak, +1 defending poison ring (as many as you want really), +1 defending boot blades, knee blades, sleeve blades, etc. and cast greater magic weapon on one or more of them, and put the (now higher) enhancement bonus from all of those to AC every single round as a free action, and that AC bonus stacks for all forms of AC... and you just attack with your main weapon as normal...
Don't you actually have to use the weapon for it to qualify?
Hype also noted that as only the +'s on a weapon increase the weapon's HP (without anything to trump that general rule) any + added to defending changed the HP of the weapon.I very much doubt it. When using the total defense action, you don't threaten anybody, which implies you're not using the weapon at all.Or just thought, using the total defense action probably qualifies.
I'd consider changing the magical status of the weapon and its HP a rather odd interpretation of how the Defending weapon property works.Pre-crash I asked this Q and Hypersmurf had some replies along the lines of (from memory so only a vague quote): if you use all the +'s on defending the sword is no longer magical and thus the defending property doesn't work snapping the +'s back to the weapon which is now + thus the you can use defending which makes the weapon non-magical again.Hype also noted that as only the +'s on a weapon increase the weapon's HP (without anything to trump that general rule) any + added to defending changed the HP of the weapon.
Defending A defending weapon allows the wielder to transfer some or all of the sword’s enhancement bonus to his AC as a bonus that stacks with all others. As a free action, the wielder chooses how to allocate the weapon’s enhancement bonus at the start of his turn before using the weapon, and the effect to AC lasts until his next turn.
I'd consider changing the magical status of the weapon and its HP a rather odd interpretation of how the Defending weapon property works.
The weapon should definitely not stop being magical just because it has the +2 enhancement bonus taken away, otherwise you would be unable to use it in the manner specifically laid out in the item description.
You do have to use the weapon to gain the defensive bonus. From the DMG:
Defending: A defending weapon allows the wielder to transfer some or all of the sword’s enhancement bonus to his AC as a bonus that stacks with all others. As a free action, the wielder chooses how to allocate the weapon’s enhancement bonus at the start of his turn before using the weapon, and the effect to AC lasts until his next turn.
Moderate abjuration; CL 8th; Craft Magic Arms and Armor, shield or shield of faith; Price +1 bonus.
To me, using in this case is rolling to hit something

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Rulebook featuring "high magic" options, including a host of new spells.