If I put the Cursed Ring on Tifa, when the timer counts down her innate is activated, as expected. However, this happens even if I cast Death Force on her: not sure if that's intended. Also, after that she can't be Death Sentenced anymore.
(Edit: I was assuming Death Force would protect against the Cursed Ring's effect, but I just found it doesn't)
Aeris can use Cid's Scimitar. It's pretty cool, but I'm not sure if that's something you did intentionally.
If that is the case, then head this way instead; the routes with a red X are supposed to be blocked off by a script:
I confirm that the path on the bottom right isn't blocked off, although I didn't explore it so I never found the bug Vineos did.