So my Bard / Necromancer is wandering through the dungeon. Army (say 6) of companions and slaves is following him. Occasionally my PC senses imminent danger... and out of depth monster appears. I'm not prepared to face it because my PC is on low HP, level is low because I'm usually letting companions to slay enemies, etc... No matter.

So I need to ask each my friend / slave explicitly to defend me from this monster. It just discourages from having more than 1-2 companions which feels odd for bards, necromancers, characters with music, probably druids...

Proposing the following:
After [ctrl+o] is pressed and you're asked to select a companion add a new subcommand: command [a]ll (or command [e]veryone, not sure what wording would be appropriate).
So the prompt would look like this:
After it is selected game would bring ordinary prompt to "[a]ttack, [m]ove, [w]ait or [f]ollow you". Then each companion decides whether to follow the order and slaves are just doing what is needed.

All this should happen in one turn, no matter how many friends PC. PC is just shouting to everyone.

I assume there will be complains that suggestion is too overpowered. I don't agree with that but I'm not against if commanding everyone would require higher charisma, would have higher failure chances or even if they would be possible for bards and necromancers only. I'm thinking of this feature more like an interface feature. Asking 20 undead skeletons to wait and then to follow you is ridiculously annoying now.