GGs you two.
Hang in there Hombre. You'll get an instinctive grasp of it soon enough. Sledge is useful enough against Relius because when he uses an Ignis Special move he's always vulnerable, unlike Carl. Ignis doesn't have any attacks that are High or Low that aren't Specials (apart from jump attacks, obviously)
Be careful with it during footsies though, because IAD Relius j.A is like a hard counter for Sledge.