Enemies near your marked enemy are blinded (Mark Mastery)

Is the marked enemy blinded too ?

This should be very easy to test. I would do something along the lines of:

Find a zone where your normal auto-attack doesn't kill rare enemies in one hit
Mark a rare enemy
Hit them with your auto-attack
If you see the Blind debuff on them (looks like a little white star, see here: https://www.poewiki.net/wiki/Blind), then it does; if you don't see a Blind on them, then it doesn't

:)

Not at home right now, anyone know the answer?

Yeah they're blinded too.