So, hear me out: If you have both of these on the table, each time you deal combat damage to a player, that damage gets copied to other opponents as well by Kediss. But Breeches doesn’t require combat damage, any damage is enough. Also, Kediss states that the original source is also the source of the new damage. So, you can get three cards exiled in a three player game. Not that you can count that as three card advantage, since there is no way you can play all of them, but it will give you plenty of options.
I’ve sort of being looking forward to this, but there’s a problem. There just isn’t anything that would make a pirates deck better. I mean, there’s a couple of really strong Pirates. I like [scryfall]Warsail Marauder[/scryfall] and [scryfall]Dire Fleet Daredevil[/scryfall], but they both have problems. The Marauder’s ability just doesn’t do much, if all creatures you control already have evasion, and Daredevil is of the wrong color.
First thing you should always do when brewing decks is figuring out what you can do with the mana. Of course, only a select few actually do this, because it’s much more fun to start with those interesting cards or synergies. Still, this is the way you should do it. (Yeah, I don’t either.)