Very rare magic weapon (great sword)
Property: You gain a +3 bonus to the attack rolls and the damage rolls you make with this great sword. As part of any action, before using the sword to attack, you can allocate some or all of its bonus as a bonus to your Armor Class that lasts until the start of your next turn. Until then, only the unallocated bonus can be applied to your attack and damage rolls with the sword.
The broad blade of this great sword is sharp near the tip and notched with defensive rills near the cross guard. An enameled shield design is blazoned at the base of the hilt, over which is inset the symbol of a gauntlet. When the blade is handled, its balance seems to shift from moment to moment—not unpleasantly, but intuitively, to match the wielder’s grip.