All conditional effects can only happen once. You can't stack them.
Gryphon stack, that is stat dependant. So therefore one would assume that arc angeling also stacks.
Unless they did something unusual in the coding, Gryphon is not a conditional effect. It is a constant effect based on your stats. It is literally
+(20 - 2* round down(base str/11)) crit, +( 2* round down(base str/11)) Luck
I am kind of curious though how do they have the card coded so that changing your luck while the card is equiped automatically updates it instead of waiting for it to be unequipped/equipped before the update occurs