I haven’t seen it as poor, but that just may be how I play it.
I use a 1-2-1-2-1-(2 or 3) build with Flame Sword + Beam Staff and it works very nicely for me. It’s sort of a damage/CC combo build and is a very proactive team play build.
I bring out the staff for quick alt-fire plumes if I need to generate overcharge and/or give a cluster of enemies a good smack, and for higher boss damage. Maybe vent if needed but it’s rarely a case.
The Flame Sword’s heavy attack is a staggering attack that also sets the enemies on fire. The burning effect from UC’s melee weapons scale with Unstable Strength, so spamming heavy attacks both keeps the hordes off balance and does good burning damage. The added effect of Enfeebling Flames which reducing the damage burning enemies do is also a great boon at higher levels since higher damage means more damage shaved off via the percentage.
Note that the Enfeebling Flames effect still applies to immune enemies. They may not take the burning damage, but they’re still technically burning. At least based on what I’ve seen, someone may be able to show raw numbers.
All that said, I agree with a lot of what you say because I see it all the time when I’m not playing Sienna.
I like the idea of damage-to-heat calculated after resistances, but am skeptical of venting with melee weapon. It feels like there’s too much best-of-both-world since she’s already really tanky.
You might be on to something there. As long as it’s talent based so it’s an option. I foresee plenty who won’t like it, but I would rock it.