I have since discovered that the cast axe head is not the end of the process. Obviously it would be 'cleaned up' ....apparently hot 'just cast' bronze is brittle so removing 'flashing' would only require a gentle 'tap' with a hammer (stone or bronze) to remove. Often stones were used to clean the head further. Then to create the hardened edge it would be 'work hardened' by use of a hammer, this was done cold. In effect , as the edge was hammered it would become thinner and harder. The bulk of the axe would remain softer. If problems with this process occured (such as minor cracks in the blade's edge.) The head would be re-heated to anneal it (soften) and then re-worked.
If during use the edge was damaged, it was possible to re-profile it with stone.......but without the 'work hardening' it would blunt easily. Several experts are amazed at the precision that the blade edge was produced by the hammering (to work harden) often requiring little or no 'dressing' with flat stones.
Unlike steel where a sharpening stone would improve the sharpness, the bronze blade would require a hammer, an anvil (rock) and a stone.
It seems to me that the 'chisel' (the axehead with the sprue still attached) would have a good work hardened end (repeatedly hit with a hammer as it was used as a chisel) With the two cast hoops it could be attached to a shaft......and presto....you have a hardened hammer to cold work harden your axe.....a worthy addition to your blade sharpening tool kit....I wonder
Regards David