Gladius Legis
Legend
I just checked back and caught that Insightful Fighting can be activated at any range, so that does make it a lot more useful. Bumps the archetype up to black as well overall, I'd say.
Yea, pick one or the other.
The more warlock, the better booming blade is, since it auto-scales.
The more rogue, the better multi-attack is, since you scale by sneak attack.\
Xanathar's updates are up. Scout is good (very good at higher levels). Inquisitive is not.
Also the few new spells Arcane Tricksters get access to are meh for the most part.
Find Familiar: Conjuration; 1 hour; V,S,M*. No reason to take any other spell with your free choice at this level. All the advantage you could ever want is there for the taking, via the familiar's Help action that requires none of your own actions. (The Owl's Flyby is especially good for that.) And then there's the also-awesome-for-scouting ability to see and hear through your familiar up to 100 feet away.
If you use the attack-aiding option in Help, the next ally who attacks the target gets the benefit.
Something I've found in my further readings that's important to keep in mind, is that due to the familiar rolling it's own initiative it's not actually "all the advantage you could ever want" since their help action gives advantage to the next player, which may not be you.
https://twitter.com/JeremyECrawford/status/854020028949086208
The Rogue can Ready their action for when the familiar uses Help, however. Thus getting the advantage from it that way.
Why would you be giving up your Cunning Action?