Here's a quick video I made to help you out. Just remember how they work, if you try to attack them while they're hovering in the air, they'll dodge up or down but if you're close enough you can still get the hit. The other key thing to know is, if you force them to dodge by almost hitting them, it resets the time it takes for them to swoop. This is pretty key so you can position yourself (I did it a couple of times, purposely making him dodge so I can run to the other side of the screen).
The other things I forgot to mention is if you see the arremer do a small swoop and stay high in the air, it means he's going to do another one immediately after it so be prepared. You can also reset his swoop timer by scrolling him off the screen, and he'll just follow you around. Just remember he'll always go to the ground to do his stupid dance if he shoots a fireball or the 3 imps if you don't attack him after, this is usually a free hit if you can point blank him and chase him back into the air.
It's much easier on this stage to lure them all back to the starting point because you have more area to deal with them and you get plenty of time for the stage. I did this with the lance, its much easier with the dagger. Hope this helps!