Unsure on all. Hard to gauge Senya's power, and Satele's by KOTFE, given that we haven't seems much out of them. Based on the fact that Senya ragdolled the Outlander, I MIGHT say she could take Force, but it's doubtful. Sabers I imagine goes to Senya, given that Satele's skills probably started weighting in her solitude, but I'm not sold on it. All-out, again, unsure.
I said she might have the edge over Satele in Force, I'm more leaning in Satele's favor though. Sorry, should've been more specific. Now that I think about it though, Satele's Force strength has probably increased a considerable amount, so I'd give her a solid edge here. In sabers we haven't seen enough of either to make a solid judgement, which is why I think that Senya would win, given that we've seen more out of her as of this time and Satele's basically a cryptic hag who sees dead people atm. I guess I'd give Satele the all-out edge since her Force superiority is probably enough to give her the edge.
Honestly the Gravestone feat is better than any of Satele's imo. But Satele can teleport now (assuming that was her and not a Valkorion illusion) so that's a big deal. I'm unsure of how good current Satele is in sabers since she seems to have been declining with age. Senya should take it regardless imo. All out is a toss up.
Senya, more skilled and probably more powerful. Satele has contended with Darth Malgus on two occassions, which is impressive but she still lost deceisively both times. Senya on the other hand has been named the deadliest of all of the Zakuul Knights, the equivalent of Sith and Jedi, and defeated Vaylin, who outmatched a recovering Outlander (already the most skilled and powerful Jedi of his generation) and Lana Beniko together, while seriously holding back. Satele is solidly outmatched in this area.
In terms of power things are more evenly, Satele's very much the prodigy her ancestors were and her showings support that, from easily crushing Hex droids to absorbing Malgus's lightsaber for a respectable amount of time. Senya on the contrary has helped lifting the Gravestone alongside the Outlander and Lana Beniko, a showing which alone would put her in Satele's league and possibly beyond that.
So yeah, Senya's the better combatant and would from the very beginning of the fight push back Satele, perhaps her utilisation of Trakata and lightsaber pike fighting style could confuse Satele and be an advantage to Senya, while Satele's powers may prolong the fight, the fight still goes to Senya.
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I'm not sure, honestly. Satele lost to Malgus but he was already one of the greatest warriors of the empire as an apprentice. She did a little better against an improved version of him later. I'd say Malgus accolades are far better than being the best in a group of people that can be one shotted by an unarmed Darth Marr.