Can you post precise measurements? As per a previous post, there is a difference in the rate of corrosion of blade and handle. This indicates a possible forge weld between handle and blade. Often blades weye something along the lines of blister steel or wootz grade Indian subcontinent steel or Swedish steel, tangs and secondary metal could be wrought iron or low carbon utility steel. Viking blades combined wrought with crucible steel very early in European weapon history.
Many pikes did not have socket tangs, they would have had a long flat tang sandwiched between the pole-staff. Multiple other ways of fixing blades including clamp-type assemblies which might explain the protrusion on the tang. Could also be a repaired pike or a mountable multi-purpose dagger pike intended for use by a sailor.
My two cents as a blade-smith is that it is the real deal, Spanishad or Swiss pike.