Assassins are hard to classify since they all usually have mobility and nuking potential so i want to propose this system
Stealth Assassins - Stealth Assassins rely on stealth to gain a tactical advantage. they may have great damage and mobility but their stealth is what they rely on the most without it they fall apart easily.
Pure Assassins - Pure assassins rely on their Mobility and Nuking Capabilities to gain a tactical advantage. these assassins usually require a good set-up to continue their onslaught. they are the assassins able to kill off a key player in the enemy's strategy and run away to either safety or their next target. they are usually the last to enter a fight and can escape when the situation calls for it.
Combat Assassins - Combat Assassins rely on their Utility, combos and timing to gain a tactical advantage. they may have great damage and mobility but they rely on either hitting their utility skills or dodging, enduring and healing back damage via using skills. they usually fall short or end up dying if they are not able to this.