The Man-at-Arms has been part of old school fantasy gaming since the birth of the game. The man-at-arms is a common man with some training and willingness to enter combat but no real capacity for heroic action or lordship. Here are some proposed 0-level aids for adventurers to hire to fill a wider range of support roles.
Some of these fellows could prove very useful for a low level party and possibly into mid levels but they shouldn't alter the power of PCs too significantly and their low saves and hp certainly limit effectiveness at higher levels where more capable and dedicated henchmen should be employed.
Friar: brothers of an order trained to support their religion and spread the faith. They may use arms and armor allowed to clerics of their faith, they may use magical items allowed to clerics and may turn undead twice per day as if a 1st level cleric.
(4 to 6 hp) morale 9, wages- 25 gp
Initiate: members of a faith schooled in rituals and rites. It is their duty to aid the more powerful clerics. An initiate may pray for 1 st level spell a day that may be cast with the assistance of a cleric. They are not able to cast the spell themselves. They are not trained in the use of weapons and armor but may otherwise use all items allowed to clerics. (2 to 4 hp) morale 7, wages- 50 gp
Scribes: educated individuals able to identify and read scrolls 90% of the time. They may use scrolls written by MUs or Clerics. if they fail to properly use a scroll there is a 10% chance of mishap per spell level. (2 to 4 hp) morale 7,wages- 75 gp
Sapper : locate traps, disarm traps and open locks on a 1-2 on a d6. They can open any \normal sealed portal (unless sealed by magic) after 2 turns of (noisy) labor on a 1-4 in 6 chance. They wear armors lighter then mail. (4 to 6 hp)morale 9, wages- 25 gp
Shield Bearer: specialized men at arms, equipped with a large or tower shield they improve the AC of their master by 2 when adjacent (if they make no attacks). Up to 2 shield bearers may defend a single person. (5 to 8 hp) morale 10, wages- 50 gp
Urchin: may move, hide. locate traps and listen as a 1st level thief. often used as scouts in dungeon environments. no thieves in your rules set: they have a 2 in 6 chance of success per task. (3 to 5 hp)morale 6, wages- 2 gp
Yeoman: men at arms that are trained archers, they attack with bows as well as a 1st level fighter. They have no skill with arms other then the bow and may not use shields against trained foes. (3 to 6 hp) morale 8, wages- 10 gp
AC should be as per armor worn. Wages per month or week depending on campaign, includes upkeep costs.