Recently I was ganked by a level 90 Warrior, while I was on a level 89 Balance Druid. The Warrior in question was really bad, and I guess thought he could get an easy kill. Anyways long story short I managed to kite him around and get him to around 30% health when he got the Second Wind Buff.... at that point I could not lower his health any further even with all CD's. Is this intended or is Second Wind supposed to make a Warrior invincible to anyone below their level?
EDIT, Tested this with 2 friends, an 89 Balance Druid and 88 Frost DK, cannot do enough DPS to kill a warrior who is in quest greens, we can get his health down 2-3% with Necrotic Strike but he heals back up again before the DK's runes are back up for more, even with the ability to recharge all his runes, we got him down maybe 10% and then he healed right back up.