A good majority of MMORPGs, well, let's be honest, all of them, identify 'assassin' as a class who wears leather armor, uses daggers, and conceals their face with a hood.
But really, in a proper setting, wouldn't that be like the worst assassin ever?
Why not use a sword? Why not wear metal armor? Why not avoid fighting at all, like, using poison or persuasion?
In my opinion, realistically, hooded figures with cloak and dagger approach are doomed to fail.
Consider modern days. Let's see, you are a policeman searching an assassin.
Which guy would you suspect to be an assassin more?
This guy?
Or this guy?

So innocent looking, open and harmless, but you never expect him to go BANG!

That's what a proper assassin should look like, a good assassin truly.
Now, medieval times.
Imagine you are a town guard on duty guarding a gate. Which guy would you NOT let through the gates without a search through, if at all?
This guy?

Or this guy?

Again,
This guy?

Or this guy?

I hope you catch my drift.
I guess this summarizes my small rant. Assassins, remember to hide in plain sight.
The more 'mysterious' you look, the crappier you are at your job.
Best assassins are harmless looking and inconspicuous, not dropping any hints at their possible dangerousness.
I mean sure, there exist assassin clans, but don't you think if they just waltzed into towns looking like badasses, they'd be quickly snuffed out and executed?
Oh right, that happened to the Hashshashin.
Look like a peaceful citizen. Blend in.