Question about Darkmoon and Sunlight blade

Ok, I never created a toon for this powers, now I have. Do you have to play through the game twice for both miracles? If you get the darkmoon blade you can't kill gwyndolin and then get the sunlight blade? Do you have to be in the govenant to use it? (the dmb)

Sorry if it's a noob question, but I never got into those aspects of the game.

For the darkmoon you get by joining the covenant and you can only use it when you are in the covenant, but if you get covenant + 1 and so on the buff gets stronger, the sunlight blade you get by killing him (its good but not darkmoon blade good), if you want both you should kill him him and go to new game plus and join the covenant

Get slb bladeon your first playthrough i made the mistake of getting dmb first, then killing gwyndolin on my second playrough...had to go to NG++ lols or join get the miracle, then kill gwyndolon go to NG rejoin baboom

Thanks for these tips.

One additional question; how many Souvenir of reprisals do I need for a maximum powered darkmoon blade?

80