So here's a new Noble Arms support. No, it's not a Fan-Fic Plot Device.

[Synchronized]

 

You can only control 1 face-up "Noble Arms - Celestios". Equip only to a Warrior-Type Xyz monster. It gains 1000 ATK. Once per turn: You can negate the activation and effect of a card effect that targets the equipped monster, then destroy that card. If this face-up card on the field is destroyed and sent to the Graveyard: You can target 1 Warrior-Type Xyz monster you control; equip this card to that target. You can only use this effect of "Noble Arms - Celestios" once per turn.

 
This one's a bit less creative than the Shark, because it is, admittedly, a Fan-Fic Plot Device, but I did tone down the effect to make it more realistic.

It stays true to the Noble Knight equip spells, except that you can only use it on a Warrior Xyz. So it's solid support to Papilloperative, Heroics, Artorigus, etc. I made the negation effect only usable on something that targets so you couldn't turn any generic Xyz into a Shi En, which I think is a reasonable fix.

So what can I do to improve it?

[Kyng's Old Account]

Base it off of an actual Athurian Sword?

 

I think its quite alright. Xyz only balances the Once Per Turn death. I will say that maybe the 1000 ATK is potentially OP due to most Warrior Xyz's at Rank 4 (for Noble Knights obv.) have generally 2000+ ATK, turning them into vicious 3000+ monstrosities.

[Synchronized]

Base it off of an actual Athurian Sword?

 

I think its quite alright. Xyz only balances the Once Per Turn death. I will say that maybe the 1000 ATK is potentially OP due to most Warrior Xyz's at Rank 4 (for Noble Knights obv.) have generally 2000+ ATK, turning them into vicious 3000+ monstrosities.

 

This is true but it also forces you to run an Equip.  Gallatin does something similar but isn't limited to Xyz, which is why the ATK decrease balances it out.  The fact that it is an Equip is almost a drawback as it is because they're generally slow(er).

[Aix]

I'd say, scrap the 1000 ATK and simply make an option of banishing an opponent's monster which this card attacks at the start of the Damage Step, like Catastor, except you have to attack. 1000 ATK is too similar to that other Noble Arms that gives 1000 ATK and having multiple cards of the same Archetype have pretty much the same effect is silly. Well, don't have too much else to say about this card.