Just throwing out ideas-- what about making gentle touch a 1d6/2 levels ability that knocks the target prone with a saving throw to avoid the prone (or not if you're looking for higher tier power), but then also letting him "overcharge" it 1/day per 3 levels (minimum 1) for the 1d6/level + knockback? it still includes the flying directly over their head for the almost instant double damage, and at high levels it's usuable enough times per day to get stuff done. If it's not enough, you could make it 1/day per 2 levels.