So your issue is in weapon switching and not JCing. I think you would know that you can double weapon switch and the game allows it seamlessly. So here is a simple combo that will help you get better at weapon switching in air, Once you start off an aerial rave of rebellion, give 3 hits and these hits are somewat automatic and there is no strict timing to land each hit. So this gives you a window to concentrate on a quick double weapon switch. You can switch immediately after 3 style button presses but the hits will take a second to complete if not half a second more , so by this time you can tap weapon switch twice. Now you will have lucifer. No need to jc the third hit of rebellion , immediately press triangle or your melee button. This will also give you another window to switch styles to darkslayer. Now, you have to JC after two pin up of lucifer with darkslayer equipped. The window to switch to darkslayer is not as long as aerial rave of rebellion(Swordmaster) but still is a two-automatic-hit window. Jus thumb roll from jump to style and you will get a darkslayer aerial rave. Now is the tricky part. Before the darkslayer hit lands, immediately switch weapon to rebellion(jus one switch and no double switch) and style to sword master and hit the style button thrice. Now you are at the beginning of the loop we jus started. Repeat the loop and you will stay in air for as long as you want.This is effective on angelos , decloaked mephistos,assault,bassilisk. With scarecrows(except mega scarecrow) however, you can repeatedly JC darkslayer once you are close enough which a lucifer air pin-up will achieve.
Best way to capitalize in air is to use 3-automatic-hit window of rebellion swordmaster which will give you a window to concentrate on a double weapon switch and wat you need to make sure is to add a jump cancelled dark-slayer aerial rave and switch back to rebellion aerial for a window to concentrate on next aerial move. Best part of DMC 4 is once you JCed, the rate at which you fall to the ground is reset giving new aerial time for a rebellion rave.You would reach the ground only in case of a mega-scarecrow. So all you need to make sure is you have JCed atleast once before you do a rebellion aerial rave. But in DMC 3, Even if you JC, You will still reach the ground, only slower. I tried it with an E&I cancel instead of a Jump cancel, well, since you reach the ground anyways. But yeah, JC makes you reach the ground even slower.
EDIT: No need to remap controls for DMC 4. Style button is sufficent for JC purposes and is closer to jump button. So default controls will do.
Hope i helped.