what is the difference between a Mace and a Morning-Star. and what would be the benefits of one to the other?
The significant difference is the use of spikes in a morningstar versus the flanges or knobs of a mace.
The mace was a professional warrior’s version of a club, with a heavy metal head meant for denting and penetrating armor. Even the best plate helmet on, taking a hit to the head with a mace was ruining someone’s day. The flanges on the mace were to concentrate the blunt impact of the weapon, to maximize the force penetration and cause as much damage as possible to the man underneath.
The morningstar was designed to defeat an enemy using a combination of blunt impact and puncture wounds. The characteristic of a morningstar was a round head with one central spike opposite the haft and the head covered in other spikes.