Finishing Moves are attacks that add a powerful extra affect while discharging the amount of "charges" currently accumulated through a Charge-up Skill.
A Finishing Move doesn't just trigger the release of the accumulated charges-it also adds a powerful effect of its own. Furthermore, by building up a succession of different Charge-up Skills, Assassins can generate a potent combination of effects.
You gain all the benefits listed in the Finishing Move plus any bonus you may have from Charge-up Skills. These bonuses are dependent on the amount of charges you have, and from what skill each of those charges came from. You can mix and match charges, for example:
You attack a target twice with a level 13 Tiger Strike gaining two charges, using a Finishing Move now will give you +680% Damage. If you instead attack an enemy with a level 11 Cobra Strike gaining 1 more charge for the maximum of three, then attack with a Finishing Move you will now gain +680% damage and 90% life stealing.
Note that Bonus Damage % is additive. If you use the above example and a level 5 Dragon Claw for a Finishing Move you will gain +750% (70% + 680%) Damage.