And then Thor gets to fight everyone! Thor gets to fight everyone, right? Thor was really looking forward to fighting everyone.
Of course Thor gets to fight everyone. Is the plan still "everyone including Loki versus Thor, less anyone who spent the last extended period of time in Doriath, simultaneously"?
So Loki puts the Tesseract somewhere which is not in Lævateinn and outlines less-brutal-than "until someone yields" rules of Asgardian combat and inquires of her sister if osanwë is cheating?
"...it may be," says Thor. "But I did let Huan sing magic... I'll allow it."
Cool. There's all sorts of sparring-grade weapons around, what does everybody want?
Loki is not going to teleport or use ice or turn invisible. She's so restrained. (She will use the heck out of Lævateinn's shapeshifting and osanwë to make this interesting.)
Thor puts Mjolnir down by the weapons rack and picks up a less legendary hammer and then she gets to fight everyone! Whee!
Loki knows Thor's tells insofar as she has any. And osanwë has been declared Not Cheating.
Thor's just plain better than her as long as Loki is not cheating. The Elves are enough to make it go on longer but they're not that strong or that practiced; they mostly serve to divide Thor's attention rather than to land strikes. Findekáno's tagged out, then Irissë, then Loki and Tyelcormo almost at the same time, and Thor is victorious.
Thor beams at everyone. "You fought well for beginners!" she says to the Quendi combatants. "I haven't been that challenged in years! And I'm glad to see you haven't lost your touch, sister!"
"As would I," says Thor. "But if my bout with Huan is anything to go by, I'd have lost to Moringotho and then I suppose Loki would've had to avenge me."
"And then I would have had to wait to have our reunion until I invented yet another spell and it would have been awful for my temper."
Thor laughs. "So it's a good thing you were the one accidentally exiled to Arda."
"Thank the Tesseract for that one, it thought I was being too boring."