Normal armors dont actually require high str to equipped. If you had good legendary gears, all your resistances should be 40%+, might even reach 50% with good combination. Try augment with your enchantment. At lvl29, you should be able to get rank 9 recipe which add 10 armor rating. You can also use potion of armor defense to raise you defense as well.
If you really cant deal with all all the mobs all together in baal's room, try pull his minions out from the room first before the door shut down. This can help a lot. I kill him at lvl28 and the quest give bout 20k+ exp.
Since I dont know your weapon damage and skill build, I can only tell you to bring more pots and move around more with your ranger. I had started a ranger recently and found that I had to run around a lot like jerk compare to my old warrior. And use mp like nobody business.