'Sharpening Stone' Perhaps?

[OntarioArch]

An online friend of mine who is a reputable authenticator/dealer identified an artifact for me a while back as a 'sharpener': as I understand it, a tool that was used to - blunt / knock down / dull - the edges of a chert point in preparation for final pressure flaking of that edge. Edges that are slightly blunted flake off sharper, crisper, and more uniformly than they would otherwise. They end up 'sharper'. I am recalling this as I study another estate sale find pictured below. The rock certainly has patina; I do not see any modern machine marks, and that groove is quite pronounced.

Could this be a 'sharpener' tool? (btw.....the name is obviously counter-intuitive: shouldn't it be called a 'dull tool' or 'blunt tool'?) Is 'Abrading Stone' the proper terminology? Thanks!

 

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[releventchair]

Interesting piece...

Groove looks quite straight to have been used as an abrader. And it's curve contrasts with most known flat surface/face of abraders.
I'm not saying it was not used as such. Just not seeing how to dull a 1/8 inch long section edge for example where a pressure flake is desired for removal.
Pushing into and edge to remove a flake works better by doing so below the "centerline " of an edge. That suggests a wavy edge more than a straight one.
Which would make for a wider groove in the abrader , if , that inner groove wass from wear from grinding edges...

 

[kansa54]

I have done a lot of flint knapping and been around a lot of flint knappers but have never seen an abrader that ended up looking like that. Suppose it could be, but I doubt it. It kind of resembles a boat stone.

 

[southfork]

I have done a lot of flint knapping and been around a lot of flint knappers but have never seen an abrader that ended up looking like that. Suppose it could be, but I doubt it. It kind of resembles a boat stone.

Not a Boat stone here is a large abrading stone / Boulder Mortar.

 

[ToddsPoint]

It would only work if the edge of the flint piece to be abraded had the same curve as the rock. Edge abraders I have seen are flat. Gary