The use of shading really helps to make this piece pop out and the contrasts between the lights and dark really help to break down the form.
To improve I think you might be able to give a bit more definition to the planes of the face as this is probably the one place that seems a little flat.
I really like the texture that you gave to the staff and the shape you gave it is very organic as well as the colours that you have given applied to it.
The forshortening on his right hand seems to be a bit off, however I appreciate that hands are incredibly tricky and combining that with forshortening results in something that is very hard to nail down.
The extra details that you gave to his design really help to elevate this piece and help to tell a story about the character without having to read anything about him.
Overall I really like this piece turned out, keep it up!