Overcharging Skills

I recently had this idea while using CSB on my new Thunder Breaker: what if you kept holding down the hotkey of the skill for a longer period of time (5 seconds or so) and that if you would release the skill then it would be stronger, have a flashier effect, have more range, maybe some side effects, you name it.

The way "Overcharging" would be obtained would be trough a quest which would be different for each job class. Cygnus Knights would obtain it trough a side quest at level 120, and for Aran it would most likely involve the combo counter.

A few skills to start with:

 Corkscrew Blow

Range: 350
Targets: 6
Damage: 510%
Time: 5 seconds.

 Piercing Arrow

Targets: 8
Damage: 900%
Effect: No minimum range, Super Knockback.
Time: 5 seconds.

 Monster Magnet

Range: 400
Targets: 8
Succes rate: 100%
Effect: 5 second stun (uninteruptable).
Time: 3 seconds.

 Assassinate

Range: 150
Damage: 650%
Critical rate: 95%
Critical damage boost: 300%
Effect: Invincibility (more like CSB, not like Boomerang Step).
Time: 5 seconds
Note: For this the whole system of Assassinate would have to be changed, that it would be like any other charge up skill but only available in Dark Sight.

Any additions are welcome.

Note: I know the name "Overcharging" sounds a little weird.