Narrow tang India stag handle problem

[Naphtali]

A problem has shown itself with the handle of my narrow [full] tang knife. The handle is India stag with its irregularly circular circumference rendered slightly flat sided - that is, side flats are greater top-to-bottom than top and bottom sides are side-to-side. There are no sharp angles; configuration is a soft, slightly oval shaped handle. I assumed the irregular striations of the stag would assure a non-slip grip. . . . Wrong-o.

When my hands are greasy or slick, I lose my grip. Occasionally, I pull my hand from the knife handle.

I must have the handle altered for a significantly more non-slippery grip. I believe I have three options.
1. Have someone create subtle finger groove or grooves. I don't know whether stag can be altered without severely weakening it, or have it crumble or chip.

2. Have the handle replaced with Micarta? or other material and have the knife maker incorporate the first class gripping surface he prefers. I suspect this is a high cost solution.

3. Sell the knife and start again. I prefer this solution least. But it does absolutely take care of the issue.
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As the knife exists, I will not use it again. Please advise me, including knife maker who can do the job nicely.