Well, i was considering some points that lead in a contrary direction to that of these marks been the smith's own (or traditional) symbol (isms).
I place myself in those days where rural civilian smiths were not allowed to make weapons from their own willing, but only if they were comissioned by (big shot) clients, for their house defences or private armies.
In such context, how could the smith have the impertinency of striking such show off marks in both sides of the blade and, instead, not the client's symbols ?
I once had a sugestion (Rainer Daehnhardt) that these could be the initials of a family with houses in three different places ... or i didn't catch the correct sense.
I would also guess that multiple equal letters may appear in the construction of coats of arms, indicating various family branches; there are ancestral families with their names starting by an S, such as the Sousas and the Silvas.
... Not that the client couldn't instruct the smith to strike the weapons with 'public' symbolisms, instead of those from his private universe.
Concerning the piece itself, i can assimilate it is a pike later modified into such quoted house defence lance. I may even admit that the iron head and the but spike actually belonged to different weapons and the seller had the idea to join them, makig a composite from his imagination.
... Just wondering. In fact i allways go for actual names or representation marks, by default, and only consider esoteric stuff when supported by actual or consensual evidence
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Fernando