Frozen_Heart
Hero
I feel the opposite. 5e has so many caster classes, and only 4 martial classes. If you want to try to play a low magic setting, you're out of luck, while this wasn't the case in other editions.So if I want to play a gladiator or a duelist, is that a knight, a skirmisher, or a warlord?
Fundamentally, I don't feel fighter is such an overwhelmingly strong class that you need to silo out capabilities that all fighters might have to some extent to keep them from dominating over the other classes. Like when is the last time you heard someone say, "I'd like to play a spellcaster, but the fighter is just so much more versatile and powerful both in and out of combat that it just doesn't make sense to play a spellcaster."
It's weird because almost no concept gets cut down into smaller pieces than "fighting man" by people attempting to extend D&D and yet the reason mechanically you cut an archetype into smaller pieces is because the archetype would have too much stuff otherwise. So you could justify splitting cleric and wizard to avoid a single class with access to all the best spells, but I think you have a hard time justifying splitting "Good with a sword and shield" from "Good with a bow" or "Good at fighting and moving at the same time." You don't need a class for every weapon and every aspect of martial prowess, so that we have the "Porter" class that is good a carrying things and hiking and a "Slasher" class that is good with whips and so forth.
There isn't a single option for a support based martial this edition. Likewise, people are constantly asking for a 'magicless ranger', which fits perfectly into an overall skirmisher class.
As for what goes where, a duelist would be the swashbuckler subclass moved from rogue to skirmisher. That subclass doesn't function anything like it should due to being forced into rogue. Scimitar/Cutlass is a pretty classic weapon for them alongside rapier, while shield prof provides the 'buckler' part of the archtype. Multiple attacks also suits the archtype more than one super powerful strike.
As for gladiator, there are so many varied depictions of gladiators that they could go anywhere. Assuming the 'armour on one arm, trident or shortsword, and net or shield', once again the skirmisher class fits best.