If its this logo
http://vignette2.wikia.nocookie.net/warhammer40k/images/c/cd/Blackmane_Sigil.png/revision/latest?cb=20140720225639 then it will just be a matter of practice copying it. I would start like this, print out the logo and make it about 1 inch. I would then trace it with a pencil a few times. Then shrink it down to the size you need and trace it with a pencil again. Once its committed to memory and you can do it with a pencil than i would try doing it with a small brush and with some paint with flow liquid to help it go on smooth. The tracing aspect will teach you mind how to do it. If you can do it from memory without tracing you can do it with a brush. No easy way to do these thing but practice and practice.
Personally i would use decals with micro-set and micro-sol to help it form around the shoulder pad. You might mess up the first 2 or 3 but one you get it will go quick.
-steve