If you want a lightweight build, you'll want to get as close to 50 Vigor as you can. 50 is the soft cap, so it's pointless going over it. Also, use the Third Dragon Ring. You should get around 2.1-2.2k HP, which should be enough to survive a few hits, although you could add the Life Ring +3 to boost it to around 2.4k. As you're a lightweight build, I'd recommend keeping your max equip load below 60 (9 VIT + Third Dragon Ring is the max you can go to), which will leave Flynn's Ring as a viable option, granting an additional 50 AR to your weapon. I apologise if you already knew this, I thought I'd say just in case you didn't.