TLDR: Weapon role is similar to Axe and Shield. Unique visuals and sounds for blocking and pushing: flaming force field, (flaming?) force nova (but same mechanics as for regular shield weapons).
How it looks: The dagger is held in the right hand and has the same model as Ceremonial dagger. A talisman is held in the left hand, and only a small part of it is visible on screen while not blocking. Sienna raises the talisman while blocking. The talisman should be small (might be in a form of Aqshy symbol or something). In case the weapon has low blockrun speed and weak dodge, the talisman should look big and heavy (a scepter).
Light attacks: Fast stabs (no swipes), only affects one target, does not penetrate armor. Less DPS than the existing Ceremonial Dagger.
Heavy attacks: Slow stabs (no swipes), only affects one target, penetrates armor.
Blocking: In first person view, Sienna raises her left hand with the talisman, and a fiery shimmer appears on the edges of the screen. In third person view, a fiery hemisphere appears in front of Sienna. OR, a fiery cocoon appears around her – in this case, the weapon should have 360 degrees block/push arc. When an attack gets blocked, it plays unique sound and visual effects (fiery sparks, etc.).
Pushing: In first person view, Sienna waves her talisman in the air, and a bright force wave radiates forward. In third person view, the same wave radiates either forward in an arc, OR in 360 degrees.
Why I think Sienna needs this weapon: Lately I’ve been playing as Unchained a lot, and I came to a conclusion that her personal survivability is awesome, yet she can’t effectively protect her team using her melee weapons, like the Knight and the Ironbreaker do. She can block hordes almost endlessly, but she can’t push them around with her melee weapons. I wish she had a weapon with high-staggering push, wide block arc and high stamina reserve. Beam Staff can be used to fulfill the area denial role but I’d rather have a melee weapon for that, and the freedom to use any staff I want.