First thing I notice is that the blade looks like it has dings in it. Does it? Or is that bad lighting on the blade? The lighting and backdrop need to be adjusted so it accentuates the sellable features of the knife. Get multiple lights to avoid shadows (use a lamp or something) Any engravings? Special unique characteristics? Those need to be accentuated.
Make me want to but this knife when I'm not in the market for a knife. These pics just won't yield top dollar.
Along with better lighting, my suggestion would be to use a different background. The weave of the towel the knife is laying on combined with shadow is what is causing the blade to appear dinged. Use a piece of poster board or a plain table top.
I agree with above especially #3, look where the back end of the blade meets the towel. Even though it is an illusion it could cast doubt as to how much the knife is worth when tying to sell.