Repair/resto question

[Bob A]

I have an old Sudanese dagger from the Mahdist era, with the typical etched inscriptions and a bone hilt, nicely wrapped in fine copper wire.

However, the resin or goop that was used to secure the blade is missing on one side. Even though the blade is fastened to the hilt, there has begun some slight movement over the years.

My question is, what ought I to use to fill the gap, to keep the whole construct from loosening further? The dagger is fairly commonplace, of course, but even so it deserves some respect toward originality and perhaps even reversability.

Thanks in advance for your suggestions and insights.