As far as we saw in Rebels, she only trained with Kanan. Sabine only found the Dark Saber well after the events at Malachor, which was the last we really saw of Ahsoka in Rebels until the bits in the last few episodes, so didn't train with Ahsoka. I'm a little puzzled by the whole "walking away from you" and "Master" bits in the trailer, since they didn't really have a relationship other than fellow insurgents in Rebels.
Anyway, I would expect Sabine to have lightsaber skills similar to Bo-Katan's, given that Bo-Katan likely trained with it more than Sabine did (though, on the other hand, Sabine had some instruction from an actual Jedi). She has her Mandalorian tricks (like the cable gun, flame thrower, etc.) that should make it a more interesting fight with a Force wielder, but she'd be outmatched.
I’m a little puzzled by the whole “walking away from you” and “Master” bits in the trailer, since they didn’t really have a relationship other than fellow insurgents in Rebels.
Remember that Rebels ended before the Battle of Yavin. There were about 5 years between the main story finale and the epilogue, which would have been plenty of time for Ahsoka to spend some time training and then subsequently abandoning Sabine ahead of their reunion shown in the epilogue.
Outmatched, really Mandalorian armour and combat training was designed to go up against Jedi They fought a war against the order after all, and also the Old Republic
Against an untrained Mandalorian The Mandalorian War ended when the Old Republic and Jedi scorched the surface of Mandalore Only way to beat them was by war crime
Dunno. But they seem to be leaning quite heavily into the "I'm no Jedi," thing. All of the lightsabers none of the dogma? I think it's an interesting way to go considering how big the sick-of-jedi-sith contingency is these days.