If thats an H.I. khukuri, the loose handle would probably fall under warranty.
However, it can be fixed without alot of fuss.
1) As yours is wood handle, i would suggest using one of those boil-in the-bag things so that you do not raise the grain of your handle when using this method. Get the water to a rolling boil and submerge for somewhere between 5-10 minutes. This will heat and soften the himalayan epoxy called Laha. Squeeze handle tightly until handle cools a bit. The Laha will resolidify very quickly and solve the problem. You may want to re-peen the handle pins a little at this time.
2) Use the more viscous type superglue, not gel type for this method.
Find where the handle is most loose and force superglue between handle slabs and tang. Superglue will adhere, but also slightly melt the laha and also help it to re-adhere. This is probably the simplest fix and may not always hold. Again, you may want to re-peen the handle pins at this point.
3) Slightly pry the handle slabs away from the tang. Mix 2 part Devcon Epoxy and apply between handle slabs and tang. Clamp overnight. Re-peen pins. Be careful prying the slabs away from the tang as it is easy to mar or ruin the slabs using this method.
4)Drill out handle pins and remove slabs by heating then with hairdryer, heat gun or boiling as above. Reglue and repin.
Methods 2-4 will require some cleanup/sanding afterwards.
Good luck!