Two movies ago, Obi Wan was disarmed hanging from a ledge down a hole with Darth Maul standing over him trying to get him to fall to his death. Obi Wan then performed a massive improbable jump over Maul's head while grabbing the slain Qui Gon's lightsaber from across the room and then slicing him in half at the waist.

It is a little dumb that the guy who pulled that move off would mention the high ground as an advantage. Though I wouldn't remove the line "Don't try it!" Because, having done that move on Darth Maul and probably taught it to Anakin, he's ready for it.

They should have set it up to where it looked more like the setup with Maul, have Anakin obviously recognize the scenario and grin, Obi Wan says "Don't try it" perhaps under his breath, Anakin jumps, Obi Wan dismembers him.

But the Star Wars prequels were written by a massive hack, so.

Yeah, right?;There should be another bit earlier on where they're sparring and the same phrase comes up, otherwise it doesn't really fit standard story telling patterns...

Or if Obi-Wan himself didn't famously flip over someone to cut them in half.

From hanging on a ledge, no less, pure upper body strength and Force magic.