Don't be getting to crazy with the blood. It deals what like 10% to yourself and how much dmg do you get from it? 15% total (50%+ on three hits, odds are 10-15% average?), so you r only really getting like 5% of advantage.
Also you need some way to actually activate the blood buff, and consider that if it's the first three hits if you do anything like poke or jab or heck if they just block your string then your probably going to end up doing little to no damage from it and just loosing out.
Honestly I see the buff more as a chip-out tool then a combo tool. If they are low you use it and then just hit them with heavy block tools or throws or sweeps so the added chip is enough to finish them.