I will repeat the same thing I always say when I talk about this card idea. I think that the ability should use instead of . Reason for this is that it fits the Crusader theme better. Crusader, although seeing themselves as the "good guys", did some pretty evil stuff, therefore .
Hmmm yeah everyone fighting for the crusades were technically doing evil but to themselves they thought it was the right path. Kinda perspective like if I was 5 years old and I see some other 5 year old playing with my toy, and I go and snatch it from him and he starts crying, to me I did nothing since its mine to begin with but to him I snatched something he was using. So it using light is appropriate.
But I wish it didn't target a weapon and instead use your weapon this way it can combine with morning glory or you won't have to wait for your opponent to play a weapon IF they have one.
EDIT: Great examples why it should use the weapon in your slot:
1. Unable to fly abuse
2. Useable skill in mono-light
3. Doesn't fail if opponent doesn't play a weapon while you use mono-light. (Note pic below >_>)
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http://imageplay.net/view/m7Gbd112439/Fail)