After using the unit for a while I think Penal behind cover with Fight to the Death and any MG with stand your ground are the best uses of the abilities.
Stand you ground sounds great until you try to move so a stationary unit like mg is perfect.
To the death beats back PanzerGren reliably if you are behind green cover, with support you can wipe fairly quickly which usually catches the opponent by surprise.
I have played a few games where catching a blob with the Fear propaganda can lead to hilarious results with a quad. I would chase them to base and pin them in base allowing me to capture points and setting traps with mines and scorched earth. Late game a blob forced retreat with Katy is devastating.
Commissar Squad (New Unit)
This new unit represents a formidable combat and utility squad in keeping with the doctrine's theme.
-5 Man Squad: Commissar Officer armed with a pistol. Commissar escorted by three Guards Riflemen wielding SVTs, and a medic wielding and SVT; medic does not need to be alive to provide healing.
-Costs 2 CPs and 260 Manpower
-Ability one - Stand Your Ground: Grants a targeted squad -30% received accuracy and -10% received damage. The squad cannot move unless told to retreat during its 20 second duration; shares a cooldown with Fight to the Death. Costs 0 munitions
-Ability Two- Fight to the Death: Grants targeted squad +20% weapon accuracy and 0.5 cooldown. Increases incoming weapon accuracy by 20%; shares a cooldown with Stand Your Ground. Costs 0 munitions.
-'Stand Your Ground' and 'Fight to the Death' cooldown set to 30.
-Ability Three: Propaganda Barrage: Calls in a small barrage of 4 shells that is similar to Fear Propoganda. 45 munitions
-Ability Four: Able to heal nearby infantry within 15m when out of combat which matches Infantry Section medical kits; 30 seconds.
20 range.
-Now able to throw grenades; same grenade used by Guard Rifles.
-Squad received Accuracy set to 0.87
-Conscripts can no longer be merged into the Commissar unit; prevents a bug where Conscripts would be armed with the officer's weapon.
-Can no longer recrew team weapons
Tested it in-game and it does not appear any of the Commissar's buffs work on team weapons.