Actually, choke is far from broken; we just need more people to hold the line. Since Ami moved, we can hold it if we use Edwin, Tantallos, Gregor, and Raquel altogether, but we can still hold fast for at least one more turn.
Stick someone, anyone at (7,17); (9,17); and (10,17); then back them up with people at (7,18); (9,18); (10,18); and optionally (8,18). Either Ernest goes and punches a few more holes in the walls, in which case he's not punching a few more holes in us, or he murderates one of us, in which case one of the two swordmasters is being wasted (has to move out of the way for Ernest to get in), and whichever person he murderates gets healed by the person behind them. They can't get through and can't target the person behind them because they can't stand on a tile with a not-quite-dead-yet person. There is also the possibility of them destroying the wall at (8,17), eliminating the person at (8,18), and punching through with the third person, but this can be solved in three ways - either kill Swordmaster F, who is sitting at 8 HP; sleeping either Swordmaster D or F; or we simply let it happen. Anyone KO'd by a Swordmaster has 3 turns to be healed, instead of 1, and this particular course would require Ernest to be, again, punching holes in walls instead of people. By putting mages at (7,17), (9,17), and (8,18), we can also take up to three swings at Ernest to deplete his HP.
We just can't panic at the Murder Blade's effect; as Sirus says, Ernest can only attack one person per turn at the very most if we're careful, and we can put them right back on their feet on our turn. If we take down his assistants, that's the very most he can do to us, and we can take down Swordmaster F this turn and possibly disable Swordmaster D with a sleep spell. The only trick is determining who meatshields and who revives. We can also, based on how the moves work out on our phase, either have Dag and Mannan back us up here or tell them to fall back on a narrower choke in the hall. Since the Ally Phase is after the Enemy Phase, they can block Ernest's moves and still move themselves. Ami moved already, but with a mount next turn, she can also rescue and flee, which pauses the death counter, or rescue and drop the person Ernest downs (if any) next to another healer.
Heck, we could probably send Chris, Marpa, and either Derick/Raquel or Riven around the corner to take down those rogues and Elite Guard A, if we wanted to play it risky.