Hey aadvancre , you should be able to use Blender's tools to paint on the ax with only the fundamentals of texturing (feel free to ask questions here or in the Community), but it would certainly help if you had digital painting experience. If that's new to you, I would really recommend checking out the concept section of this site:
https://cgcookie.com/course/introduction-to-materials-and-texture
https://cgcookie.com/exercise/exercise-painting-on-the-light
https://cgcookie.com/exercise/exercise-18-painterly-style
Happy painting!
Ok thanks, that's really new to me so yeah i'll check the links you recommend me first ! :)