your playing the class wrong... maybe. Also do you have any sort of melee speed, coz i can make my arc spin very fast indeed.
The class is not made for for tank just remember that, cinders job is to max dps in a very very short ammount of time while
trying to maintain survivability.
any type of pvp pyro should have space divider no matter if your str or wis based (if not speed achievs)
LF + space divider + arc
if you make succesfull hit with LF you need to teleport towards him with space divider, as soon as you push space divider hot
key you need to push and hold arc, as you come of of the divide arc will already be in animation.
you need to time your phoenix along with Thermal screen, the cinder class may offer high dmg but it most certainly is not easy to play, good luck.
one more thing to note.... most of cinders dmg comes from the critical buff and you dont have time to stack that in lamento.