And it's also almost impossible to edgeguard him.
I don't know what Reflex has in mind, but here are some ideas that I've had success with when testing Ike's recovery. For high Aethers, you can beat it out with (very) well-spaced FAirs, UAirs, and BAirs. For low Aethers (edge-level or lower), you can try stomping or edgehogging. However, if you go for the edgehog, you must grab the edge as Ike throws his sword. This may seem unreasonable, but considering how people have gotten accustomed to edgehogging Marth (who has a slower up+B), it's not that bad once you get used to the timing. The only time you'll get spiked is if you time it too early, otherwise the ascending hits of Aether should pop you up and out of the descending spike hitbox. If you manage to grab the edge as Ike's sword is going upward, you can drop from the edge, UAir, then double-jump and up+B; if done properly, Ike should jump right into the reverse hit of the UAir. For video demonstrations on hitting Ike out of Aether, you can reference
this video for high Aethers (Ganon isn't in there, but hopefully it'll give you ideas on the timing; even attacks like Falco's DAir can hit Ike out of Aether) and
this video for low Aethers.
As for QD, probably the best way is to either BAir or get under Ike and double-jump UAir when he goes over you. The latter method should minimize the chances of getting hit by QD attack. The QD walljump -> Aether is a bit unreasonable, but you can either try walk-off stomp to hit Ike before he touches the wall or wait for the wall-jump, grab the edge as Ragnell goes upward, and then drop down with an UAir as described above. At low %s and on certain stages, Ike can probably just QD walljump and up+B again though.
I hope this helps. I'm going to play Mad today, I'll record some matches of me using characters that aren't Ike (including Ganon) so that edgeguarding Ike seems clearer.