he has 3 seconds cooldown on Q, steals up to 40 attack damage with it and debuff lasts 8 seconds, slows 70% for .1 second
It has a four second cooldown.
It gives him 20/25/30/35/40 AD and reduces the opponents AD by HALF that.
The slow is 75% for 0.1s (which is only there to let him get one more autoattack since the animation itself stops his movement.
W which gives him movement speed and attack speed,
This only covers a small area of the map and can be easily moved out of (unless you get too close to a wall or fight in a jungle corridor).
E that is a great slow and I guess it could be called a gap closer
I don't think you actually know what a gap-closer is. Those abilities move the champion themselves (typically either as a blink or a dash) to a new position. CC abilities are not necessarily gap-closers unless they also provide a dash/blink.
his ult even steals armor and mr, which reduces dmg taken, increses dmg dealt, and heals him.
Yep, that's what the ability does. Disengage whenever he hits you with it can reengage after it ends. Ultimate abilities tend to be strong (hence the name and generally long cooldowns)
Also, listing the abilities in a champion's kit is not a good argument. Every champion has abilities which can make them sound OP without context since you aren't factoring in their weaknesses or limitations compared to other champions and in other situations.