Identification needed.

[Wallys-Cast]

I think Dave was near the mark with bait boat anchor and I believe it's a light grapnel for tethering a rowing boat or canoe to the bankside while fishing.
It is beautifully made whatever it is.. let me know if it ever comes up for sale.

Wal.

[Reedling]

I think the answer is found but...what a lovely item to have sitting on the side with a few other interesting curios, maybe a Salt glazed stoneware inkwell and an old cut wine glass etc.

[Lea Dweller]

That'll be a weedcutter and a very old one too, I have a much later one, see below.

I agree, it seems the most logical use for this device. The fact that the blades are still pretty sharp after being submerged for many years, would also point to it being a weed/reed cutter.