Been trying out unchained a bit its got some issues like how hard it is to maintain high overcharge it just decays off too fast and you seem to only have talents to help get rid of this precious resource.
But the key problem is sienna just has meh for melee weapons. there all useable and ok but there all very average or a bit worse. sure the new dagger does some work the swords are useable the mace has for me at least a bad attack pattern.
She needs a Halberd , a glaive, wardancer blade , twin axes level of fun and depth weaponry.
How about a nice big fiery chain?
normal attacks - two repeatng attacks , downward forward lashes going across the body hitting a narrow line directly infront of her (nothing else dos that!)
Heavy attack could be a low penetration high atack whip like attack
Push > stab could be a circular knockback move
and have it so the stacks of unchained affect the state of the chain , at no stacks its just a simple metal chain , low damage no dot and as the overcharge rises and the stacks grow it could be more and more fiery , increases its stagger and leaving a burning dot.
For the mace, block cancel into default attack will help your elite slaying habits. Autoattack into charged attacks will help you deal with hordes.
For dagger the opposite, 1st special attack into block cancel to repeat the fire slash will deal with hordes pretty well with some dodging and weaving and the second charge with elites.
As for her passives, try to use it as a mechanism to be beefier more so than relying entirely on the melee damage to turn yourself into a melee champ, a lot of Sienna’s damage is always going to come from her staff if you want to be efficient and pro-active with her. I’ve been absolutely melting things with dagger beam and mace bolt and vice versa, while the other staves seem at least viable too (although they depend on how dependable your teammates are if you seem to use anything but those four weapons mentioned above)