Dirt

It's not dirt. I think it is rather sweat from when you are training.

By the way, your choice of H3 on the Korbel is rather unique to me (ie, most players I see using the Korbel is either Bryce or Sriver)

If you want to use sandpaper, then use a fine one, like 800 mesh or finer so you can avoid taking off the wood too much. If this kind of dirt is bothering you too much, after sanding it you can lightly coat it with polyurethane or wood varnish. 

lol, are u kidding me. you're worried about dirt on the handle where your hand constantly rubs against. do u think about things before u post them.

Don't worry about that bit of dirt man. Just make sure you leave you blade out of the bag for the sweat to dry after playing.

To geogark:

The shop owner where i bought my blade and rubber from told me is a good setup. It is very fast, and wahts more i got Sriveer on my fh already

one time I was playing with my bty legout off blade, my hand sweats a lot and i guess it built up and I smashed a hit and one of the wood layers on the handle flew off!