Hello,
From a purely physical perspective, the more spikes, the less penetration, no?
This is akin to walking or laying on a bed of nails. The force imparted by the swing is distributed over multiple points of contact, thereby reducing the force in any one point. Furthermore, the many angles of all the spikes would prevent any one spike penetrating too far as they would catch on the exterior of the wound.
My take is therefore that using such a weapon on unarmoured bodies could certainly cause nasty surface damage and probably blunt trauma as well but it would not be as effective on armour as the round ball, heavy stick, hammer/pike variety.
In regards to ceremonial use, the more decorated the offensive part of the weapon, the less likely it was used in combat. High maintenance and generally less resistant. So heavy koftgari/inlay/carving/engraving on the mace head or the blade, particularly close to the edge indicate less likely combat use. The bull/demon head maces are basically hollow and are relatively thin sheets of metal - will likely deform on impact, dispersing much of the force
Emanuel