3 F'ing things. First, there's an old saying in the Army...

[The Velveteen Ocelot]

1. Sad. Anybody with an ounce of humanity in their heart

would be able to come up with some words of sympathy that didn't sound fake, stupid or insensitive. Sometimes "I'm sorry for your loss" is enough because you're acknowledging the person's grief - sometimes that's all that's needed or expected. You cared enough to express your sympathy, and that means something to the person receiving it. It can be "hard" in the sense that being in the presence of another person's grief can be really uncomfortable and saddening - at least, to people with souls - but it's something everybody has to do from time to time, and the words should not be hard to figure out.

And here's another thing. Trump said the other day that he'd already contacted most of the families of soldiers who'd died since he took office. That this was a lie was established by the discovery of emails between WH staff and the DoD that were sent the day he made that statement, in which the WH was frantically trying to get all those names and contact info so they could contact the families and make it look like Trump hadn't lied. But there's more proof he was lying, and right from Kelly's own mouth: He said Trump said something like "he knew what he was getting into" because Kelly told him that's the sort of expression that was used among military people when someone was killed. Just apart from the fact that an expression like that might be appropriate between two military men but not at all when said to a young widow, the fact that Trump asked Kelly what to say to Sgt. Johnson's widow because he didn't know how to handle these calls proves that he'd never contacted any other family before!

And, of course - as you said - he shouldn't have had to ask how in the first place.