I think his head is a bit large and that's it for the anatomy :)
I made the pose by mixing two references. Since the two pictures looked approximately similar in perspective, I guess the (wrong) shadings are making an illusion of anatomy disproportions :/

Back to your question kkots, here's how:
-I placed a copy of the finished samurai on top of the main symbol
-I added a white glow filter making it a inner glow with low blur effect (2-5 on both axis)
-I turned on the "Knockout" check box so only the glow is left
-I lowered the transparency of the symbol
-I set the blending mode to "overlay"

You don't have to follow every step and you can always play with settings as much as you want
until you get the best match