Second Wind is a terrible ability and either needs redesigned or outright removed.
1) It barely heals for 10% of the user's max HP, often less than that (6-8%). Potency based heals on non healers don't heal for much.
2) It has an insane 120s CD. It heals for far too little for the cooldown. 7% max HP every 2 minutes is ridiculous.
Second Wind at lvl 90 (non crit) heals for ~8000 (which equates to 4000 a minute), which is about what the level 70 HQ potion heals for (3600 health per minute).
When I say Second Wind is weak, that's one of the points I mean. At level 90, tt's equivalent to a level 70 potion (per minute heal.)
Possible solutions:
1) Easiest solution, give all physical based DPS Bloodbath and call it a day. Let DPS heal themselves based on the damage they do, not a potency metric that doesn't meld well with their role.
2) Remove Second Wind from melee and redesign it for physical ranged. If you're going to keep the potency based healing, make it a regen.
500 potency, 12-18s duration (adjust duration for balance).
Edit:
CBU3 has added a new health potion "Hyper Potion" that Restores up to 25% of HP (11000 points max) with a 1m 15s CD making Second Wind even more useless.