Lahna is going to kill Sazh one of these days. How he made it out alive from her wrath we just don’t know
Something a lot of people don't realise is that Lahna was a top-class Atlas analyst before retiring alongside Sazh to set up the ranch where she works as the manager and coordinator for a lot of the things it does. The ranch is basically their child, just as much as Dajh is.
The reason she gets aggravated at Sazh about doing stuff like this is because she's one of the few people who knows his entire service record. Sazh has a nasty habit of pushing himself too hard and getting involved in insanely scary stuff that would kill anyone else. Until Saviour arrived, he basically had the most powerful combat analysis and combat perception Semblance in the world.
This meant that Sazh was extremely dangerous. Think the John Wick /Equaliser of Remnant. His Semblance can't conjure weapons or unleash attacks like Saviour, but you give him time to get a suitable weapon or prepare, and he's absolutely going to put you in a box.
And trouble seems to find him, no matter what he does, and Lahna knows how close he has come to dying on so many occasions. She was, actually, his handler back in those days, which is how they met.
Sazh's codename as an Atlas specialist (which he did on the side - publicly he was a pilot) was Excalibur.
Why?
If he was deployed into the field, Atlas won.
To this day, only the most senior members of Atlas military (e.g., Ironwood) know that he was Excalibur.
Lahna's callsign was Merlin because she was something of a wizard when it came to getting Sazh the support he needed in the field and conjuring up answers when he radioed in for intel and a backup plan.
Both of them made a very deliberate choice to not encourage Dajh to go into the military. They didn't want that for him, knowing that he'd probably be pressured to follow in Sazh's footsteps since his Semblance is something similar.
The reason they only have one kid (Dajh) is also the reason Sazh stepped down as Excalibur and set up the ranch with Lahna.
I really should do some snippets on Sazh's backstory because he actually has one of the crazier ones.