Equip only to a "Noble Knight" monster. It cannot be targeted by an opponent's card effects. During your turn, except the turn this card was sent to the Graveyard: You can banish this card from your Graveyard, then target 1 "Noble Knight" Xyz Monster you control; Special Summon from your Extra Deck, 1 "Noble Knight" Xyz Monster with a different name, by using that target as the Xyz Material. (This Special Summon is treated as an Xyz Summon. Xyz Materials attached to it also become Xyz Materials on the Summoned monster.) You can only use this effect of "Noble Arms - Excaliburn" once per turn.
