Actually, it doesn't look like Reaper's mask...

Reaper's mask takes on the skeletal skull of a crow, symbolic to Death.

However, it this looks similar to Death in Darksiders 2, the mask is very, and i mean, VERY, similar. So that's probably why Blizzard couldn't make the similar design mask, since THQ Could of sued em', like they deserve it.

And Death (DS2) Is rather edgy and serious, barely jokes. But when he does, it's an insult that reaps.

Crawling in my skin
These wounds, they will not heal
Fear is how I fall
Confusing what is real

There's something inside me that pulls beneath the surface
Consuming, confusing
This lack of self control I fear is never ending
Controlling
I can't seem
To find myself again
My walls are closing in
(Without a sense of confidence I'm convinced
That there's just too much pressure to take)
I've felt this way before
So insecure

Crawling in my skin
These wounds, they will not heal
Fear is how I fall
Confusing what is real

Discomfort, endlessly has pulled itself upon me
Distracting, reacting
Against my will I stand beside my own reflection
It's haunting how I can't seem

To find myself again
My walls are closing in
(Without a sense of confidence I'm convinced
That there's just too much pressure to take)
I've felt this way before
So insecure

Crawling in my skin
These wounds, they will not heal
Fear is how I fall
Confusing what is real

Crawling in my skin
These wounds, they will not heal
Fear is how I fall
Confusing, confusing what is real

There's something inside me that pulls beneath the surface
Consuming (confusing what is real)
This lack of self control I fear is never ending
Controlling (confusing what is real)

Umm it looks more like Death's mask from Darksiders 2... It looks nothing like Reaper's mask.