why is my barb has low damage?
Which one?
You have 8 Seasonal Characters on the Americas Region, 2 of which are Barbarians. One is naked (no gear at all). The other one has almost 1.4 mil DPS sheet damage.
You’re using Travs+Compass rose instead of Convention of Elements and Flavor of time. You’re using wind shear with BK2 instead of Blood Funnel. You’re lacking substantial crit sources on your gloves. Your Lamentation has a lowish roll. You’re running ferocity instead of into the fray. You should be running at least Taeguk and Trapped, the third gem is up to you.
Playstyle you just need to not die, and make sure WoTB is up 100% of the time, making them bleed by hitting them with whirlwind is all of your damage. Don’t spam abilities, since zodiac only works on one spell cooldown at a time.