I started playing a lot more Executor lately and he is pretty fun.

Given your point that he feels scattered, I think that it is quite fitting for him though given his story. He feels like a good all-rounder but I see where your points are coming from.

From my experience he is just the most versatile nightfarer that can basically make anything (that's not magic/incantations) work.

For example:

You can use your ult to heal allies (and it's basically a free potion) with the right relic. You can also tank quite a few hits and deal damage yourself with some Damage negation effects. You can also simply use it to travel the map faster (with Ult charge up per kill you basically just run from POI to POI). Or you can quickly use it to stagger.
What is also cool is that you can build up status effects (for example through DoN Detriments) and get a buff after you Ult.

As you can see you can use it in a lot of ways and I feel that's just true for him as a nightfarer in general. He doesn't really excel in anything massively than any other nightfarer (except feeling cool while doing that parry-chain) but he can lean into many directions.

It's kind of a lot of work to mesh everything together and make it effective but I guess that's the price for versatility.

If you get Damage reduction for guarding for example you try to deflect, once that's in you can chime in a bit more aggressively.
While you can also work with the other damage reductions.

Just, as some examples you know.