Iron throwing knives -vs- Carbonite TKFollow

I bought a Throwing Knife sheath and bought the iron TKs for 6cp. Then i noticed carbonite TKs and saw they were more expensive, 19cp.

Is there a reason to go for the more expensive TKs?

The difference here would be the damage output. Keep in mind that if you dont do any auto attack damage with the throwing knives, then you have nothing to worry about, as it wont effect the damage of your combat arts. I find that (with a bow, should be the same thing though) if I use say carbonite arrows when Im fighting (lvl 53-57^^^ mobs) that I do about 90-110 on an average auto-attack bow shot. Now, I tried using fulginate arrows, since I cant find indium anywhere, and my normal auto attack bow shot is about 400 or so. So basically, unless you plan on kiting mobs with your throwing knives, or standing back in a group and doing ranged auto-attack, then iron will work just fine.