Blake has had a really boring subplot that has held her back over the last two years of RWBY, but that isn’t really her fault. She’s still a fairly strong protagonist and her Gunblade skills will be too much for Jack. He can grab his hatchet, but it just won’t be enough to tip the scales in his favor. He’s completely outmatched here and even if he was 10 years younger I don’t think it would make much of a difference. He’d still be outmatched. Blake wins.