I don't think that it would be a psychology discipline, probably more likely to be biological or maybe psychic would be its own field.
I would envisage something along these lines:
Force I: You develop an understanding that all things are connected.
Sense I: You may specify that an attack will only take place if the odds of victory seem favourable(G.M.'s Discretion).
Sense II: If a unit loses its combat by 40 or more the unit retreats and the combat is considered to not have occurred.
Force-user I, Force-Sensitive: Infantry, attack -2, defence -2, all units in the same territory gain +2 to all rolls but only one such bonus applies to each unit(command 2).
Force II: You discover that the connection can be manipulated.
Sense III: If a unit loses a battle by 20 or more then the unit retroactively retreated instead of fighting.
Force-user II, Force-Adept: Infantry, attack 6, defence 6, command 2, command increases to 4 if it has no move orders in the current turn, may enter a foreign territory without triggering combat(infiltrate).
Mind-Trick I: Choose a single territory, prevent foreign actions other than attacks from occurring inside that territory.
Force III: The surrounding space can be manipulated to a fine degree.
Force-User III, Force-Apprentice: Infantry, attack 12, defence 12, command 4, infiltrate, random chance of event if not resting(100+-81 cause a random enemy unit in the same territory to rest, 80-71 destroy a random enemy unit in the same territory, 70-61 rescue a captive, 11-20 captured and forced to rest, 1-10 destroyed), if resting in a foreign territory they do not recover naturally from rest and have a 20% chance of being destroyed each turn.
Force-Weapon I: Force-users gain +10 against energy-weapons.
Mind-Trick II: Choose a single foreign territory adjacent to one of your territories, redirect half its income this turn to your own treasury.
Force IV: Certain individuals can influence entire regions.
Sense IV: Foreign random events are less likely to damage you.
Force-User IV, Force-Master: Infantry, attack 24, defence 24, command 16, command 8 to adjacent territories, may choose to attack a single specific unit at the start of a battle, may specify units that it will not attack, infiltrate, event chance if in foreign territory and not resting(1 destroyed, 2-10 resting, 51-90 if captives present rescue one otherwise force random foreign unit into rest, 91-100 destroy random foreign unit), if resting in a foreign territory they do not recover naturally from rest and have a 10% chance of being destroyed each turn.
Mind-Trick III: 5% chance that a unit will retreat instead of fighting one of your units.
Force V: One who truly masters the force can achieve anything.
Force-User V, Force-Legend: Infantry, attack 48, defence 48, command 32 to all allied units, the first time this unit would be destroyed in a turn it is not(in combat treat it as a new unit joining the battle), if it is the only allied unit in a foreign territory then there is a 40% chance after each battle victory that the territory will surrender, each turn there is a 5% chance that this unit will assume command and your empire will become an aggressive N.P.C. state until it is destroyed, if this unit is destroyed twice in one turn then it generates a Legendary Tomb building that can double the command bonus of a resident force-user at the risk of resurrecting the Force-Legend as an N.P.C. state in control of that territory and all units within it.