I recently chipped the tip off of my la griffe (i practice using it by filling up old gallon milk jugs with water) after I carelessly swung it into my barbecue grill. Anyway, instead of sending it back to emerson i got some run of the mill sharpening rod from a local sporting good's store (it has a flat edge, a recessed groove for sharpening fishooks and a tapered end curved blades). I think it's some crappy ceramic/diamond dust thing and I can't remember who makes it. Anyway, and this worked for me...no guarantees.
I found that if I used honing oil that the metal came off the knife a lot faster. I was actually able to fashion a semi-tanto point onto mine so that if I ever do have to stab something with it, I just have to apply pressure at an angle up or down (it's still curved and most effective using a controlled swing). Anyway, try honing oil if you haven't. My blade isn't as razor sharp as it was (probably due to my lack of experience sharpening by hand), but it's sharp enough to go through a plastic milk jug full of water w/o me feeling any impact resistance (and an apple w/o getting stuck). I doubt that I, personally, can get it back to a "razor" edge w/o some specialized equipment to 1) make sure that edge is true and even and 2) apply totally even pressure during the sharpening process. Still, I carry my LG for protection and it's more than sharp enough for what I would use it for.
Also, if you do use oil, I found it most effective if I frequently clean and re-oil the sharpening rod (just use q-tips and put a towel underneath your knife to catch any run-off. Good luck. [My total sharpening time, including fashioning the new tanto edge, was around 4 hours over two days...but now it's a blade that's personal to me, not just something I bought in a store]