Akuma insaido

Its a sketch i did at school today. I liked it thoug the blade is to short
I will design it in photoshop and make some minor changes... If u have som tips what i could change, just tell me so i will think about it.

Info about the sword:
Akuma Insaido (悪魔インサイド - Devil inside)
Gives u the ability of a third eye and imens power. He sees what u dont see. But its not u who choose this sword to wear, this sword choose his owner by itself.
Some peoples says, if u sacrifice something very precious, it could become yours.