It is likely that only silver was the intended alloying element.

Except for native silver, which is very rare and usually mixed with gold, most silver is extracted from sulfides where it is mixed with lead (because silver ions and lead ions have the same size), so simple smelting will produce a mixture of silver and lead.

There are techniques of purifying the silver from the lead (i.e. "cupellation"), which were well known in later antiquity, but, at the time of early tools like this, probably the purification was not yet efficient.

The knowledge of the fact that pure metals are soft but mixing them makes hard metals is extremely ancient. Before learning this, metals could be used only for jewelry (except for very rare natural alloys, like the meteorites made of Fe-Ni-Co-Ge, which were the source of the oldest iron-based tools found in Egypt and elsewhere, thousands of years before the discovery of how to extract iron from its minerals).

Before discovering tin and the bronze made from copper and tin, which happened relatively recently, around the time when written history also began, for many thousands of years various weaker copper alloys were used, but which nonetheless were much harder than pure copper.

The metallurgy of 3 metals, lead, copper and gold, is very old, around ten thousand years or more. So more time has passed from the time when the techniques of smelting metals and making objects of them were first discovered until the discovery of other metals, e.g. silver and tin, and the diversification of metal-working techniques, than since that moment until the present.

There was a lot of time for refining the techniques used by smiths.