OK, Iron Discipline makes Comrades resistant to Fear and Pinning and Into the Jaws of Hell makes them immune to it.

So what???

They only fail Fear or Pinning is their associated PC fails. If their PC suffers from Fear or Pinning and they don't, because of these talent, they still can't really do anything… because the only actions they are capable of taking serve only to provide their PCs a bonus to actions which they are unlikely to take while Pinned or under the effects of Fear.

So why would anyone take these talents? What am I missing?

Technically, the Comrades would still be able to enact actions that don't require Challenging tests (page 201, Other Actions). That being said, I think it's somewhat sad the Sergeant and Commissar can't use Into the Jaws of Hell on the player characters.

I'm definitely for these talents being able to affect fellow PCs, providing they're following the orders/lead/example/etc of the character with them (and said character isn't running away/pinned themselves). As it is they're massively less useful than they were in the other 40k RPGs, especially since the wording leaves it ambiguous about whether they'd work on non-comrade NPCs under the command of the PC.

It depends on the situation.

When Pinned, your character can still return fire at -15 (with Ranged Volley), which otherwise would not easily be possible depending on where the Comrade is. In the case of Fear tests, having Comrades that are resistant to Fear is actually useful in drawn-out combats. The book says a Comrade always flees when failing a Fear test, meaning they are taken entirely out of the fight. However, PCs can suffer Shock results that only hinder them for a few turns and once they snap out of it they can continue to kick ass with their Comrade, who would not be there anymore without Iron Discipline/Into the Jaws of Hell.

The above being said, I still am not a fan of the implementation, but there IS actual use for these talents as they are now.

no one in their right minds would spend exp for talents like that unless the work on PCs too.

I understand the logic behind not making them work on PCs: they didn't want them to be automatic takes for sergeants or comissars and they wanted players to feel afraid of artillery barrages, snipers, and the like; making them take pinning tests helps connect players to that reality. They failed to recognize that not letting it work on PCs would make it ****. The simple solution to preserve the feel and yet make them good is to turn these orders into a reaction instead of an aura, let the sarge inspire his men to charge through the fire to victory, maybe making them waste one turn while they try to restore order to a unit. My 2 cents has been thrown.

Note that these Talents were never meant to benefit other PCs. In BC it's stated outright, in earlier systems it's implied by the wording and I believe there was a rules clarification to that effect as well.

That said, the new version is the worst one yet. In BC and DW, you have Minions who can benefit from the Talents and can be a significant force. In every system, you could hire or sway a bunch of guys, whether you're an Astartes taking command of some Guardsmen, a Rogue Trader leading a mercenary detachment, or a demagogue leading an angry mob, and in either case, the Talents let you get an extra mileage out of these men. But now, it only affects Comrades, and they are just a bunch of floating buffs, extremely limited in numbers and usefulness both.

@Morangias

While BC contains the clarification (and it's more or less appropriate there - Heretics will usually be too independent from each other to be that much affected by another's presence), Rogue Trader for example does not. And classifying a Rogue Trader's retinue as anything other than "followers" would IMO be difficult.

All these talents require the leader to remain firm in the face of adversity themselves, or at least I believe that's the spirit of them. If they fail a fear or pinning test then their squad isn't going to draw any confidence from them cowering and/or weeping in terror. Nor are they if they're dead or disabled. The character becomes a linchpin for whatever force they're commanding; they provide it with a massive benefit, but they're also a high value target for the enemy.

I think the main difficulty with it affecting other PCs (which it should) is establishing whether they consider the character with them their leader. It's a roleplaying issue, something that both the GM and the player need to come to a conclusion about for the character in question. A disloyal and self-serving guardsman may not give a **** if his Sergeant has Into The Jaws of Hell; he's not going to risk having his head shot off for the sake of some heroic bull. The Sergeant can in turn try and inspire him to do so, whether in the heat of the moment or over time. Under the current rules this can never happen; no character can ever have enough confidence in their fellow PC to draw inspiration from them because it's mechanically impossible. It sidesteps the aforementioned difficulty, but it also sidelines an opportunity for development between characters and makes the talents quite unattractive, given the cost of acquiring them.

What if to make it a re-roll of those tests if Into the Jaws, and maybe a +10/+20 if Discipline but not being immune to them?

And works only if one who has it pases the test

But it must work on PCs too because comrades who are more fearless than PCs sounds silly