Fuck you, and fuck your roof. You're dead mate.
God, that felt good.
A little advice for anyone interested re. Boss GA:
You gotta learn the patterns. My method was to stay close, do two attacks then guard to see what he did next and then react to that. Keep on him or he'll try and shoot you. If he jumps guard *immediately* because that arrow salvo is a fucking nightmare that I never quite managed to get down. Also, his general attacks don't really change. Ever. First pip the deadly blows will pretty much always be mikiriable thrusts. Second pip it could also be a swipe you're supposed to jump. Watch out for the different tells, his blade sparks before he pulls off the move, and by where the spark is you can tell the attack and react appropriately. Also, you probably got some information just before you came up here. It's relevant. Be ready.
It's a real test of knowing how the game's combat works. Slash one time too many and you won't be able to block the jump attack and be ready for the thrust, or you'll be hit from your right side when you should be blocking. Otherwise, there's no trick, no cheese, you just have to do the thing.
End. I believe in you all!