The situational malus sounds a fair trade to me.
What about Darcozzi tho I really like the PoE 1 Darcozzi Observer build, but in Deadfire they only have gimped flame shield and a weird malus.
Good question. I was just spitballing. Less Zeal is hard to build off of, so it'd probably have to be something brand new. Can't think of anything off the top of my head, but my instincts tell me lowering Deflection while active? More damage, sure, but more chances for the shield to go off.
I like the penalties in the vein of kits in baldur's gate, but I don't like the idea of specializations being tied to an order and it's ethos. You shouldn't feel like you're being punished by making a damage dealer paladin that isn't a bleakwalker, but if your other options are to gain a bonus you don't need AND get a penalty. That feels too extreme. The other option is to make a bleakwalker and get the bonus you want but also a penalty and a further penalty if you don't role play your order via Faith and Conviction. Faith and Conviction also prevents there from being a no subclass option as it is implemented now.
I think that from the get go subclasses have been advertised as opening up new possibilities. I remember them saying how many combinations of subclasses there are with dualclassing. With the penalties it felt very limiting, both in build and in roleplay. I would be okay if all the orders did was determine your starting ability and ethos for F&C. I can see why others might want something more substantial though. Keep in mind there are something like 11 classes and 39 subclasses and there is no way they can justify a lot of exclusive abilities for all of them even if they could come up with that many unique abilities.
I think a reasonable compromise would be something like each order having a few bonus abilities from other classes available as a sort of light dualclass kind of like the dualclass talents in PoE1. Bleakwalkers could get sneak attack, withering strike, and shadow step. That would be very themeatic, but by no means mandatory and you could always ignore your order specific abilities to get shared paladin ones. Shield bearers could get fighter stuff, I'm not sure about goldpact, darcozzi or kind wayfarers. Darcozzi would probably just get flameshield and fire stuff. Kind wayfarers would just get a mix of priest/druid heal spells and goldpact would be the hybrid 'specialization' getting a mix of offensive and defensive 'veteran mercenary' themed abilities from barbarian/rogue/fighter.
For argument's sake, I'd say that a Paladin order would be probably one of the few cases were combat abilities should be tied to character's personality, since it has to do with loyalty to a way of life or code of conduct or whatever. (Personally, I don't care that much)
I like giving Paladins other class's abilities on paper, but if I had to object to it (which I don't), it would be that firstly, Priests already get that, and secondly, Paladins are already good at doing just about anything you need in a party (tank, heal, dps, buff/support, even some CC). Giving them MORE OF THING just seems unnecessary, and judging by the response of others, would fall into the same problem that the current build has: More Better At ThingTM isn't an interesting choice, and potentially game breaking. Truthfully, I'm more bothered by the overlap with Priest.