While any class can take any background and there are obviously options - there are no options that really boost Martial characters the way that the ostensibly Martial backgrounds boost non-martial characters.
Rogue's are technically Martial classes, but this post is focused on Fighters, Paladins, Barbarians, Rangers & their Subclasses
Example 1:
SELLSWORD: Would appear to be a background that could "fit" someone's concept of a Martial character.
However none of the benefits truly add value to a Martial character such as a Fighter or Paladin.
SOLDIERING: Athletics and Intimidation are the granted proficiencies. The problem is that Martial classes often have very narrow lists of Proficiences, and both of these are already on it (except for Rangers who do not have Intimidation as one of their options). So these two "bonus" options do not expand beyond what most of the Martial Characters can already get.
ARMORED: Proficient with Medium Armor. This adds no value to any of the Martial classes (Fighters, Paladins, Barbarians, Rangers) who all already have at least Light & Medium Armor Proficiency.
Example 2:
LAWKEEPER: Another Background that would seem very suitable to a Martial Character concept
DETECTIVE: Perception & Intimidation. Slightly better than Sellsword here, as Perception is not on the Paladin list and Intimidation is not on the Ranger list.
ENFORCER: Proficient with Martial Weapons. Again, as with "Armored" above this is basically useless for Martial Characters.
Being able to add some of these options to Non-martial characters are great - especially Armored & Enforcer. Yet, for Martial Characters these backgrounds add very little if anything.
On the whole, I think backgrounds need a look over to make sure they all add similar value and that there are options for all classes that can expand on what they get in their base class.
I always thought that backgrounds are not supposed to be viewed as a source of extra power for characters.
What they do is add a bit of flavor and provide a number of personality traits.
Yes, some backgrounds have better synergy with some classes, but so do some race/class combos.
So I suspect if there would be a real uproar to "balance backgrounds across all possible classes" the simplest solution would be to remove the bonus proficiencies altogether.
I disagree. I think that backgrounds that give different profs are an interesting way of building a character that might make sense from a roleplay point of view but might not be able to be created otherwise due to mechanics. I think that the lack of multiclassing in particular makes stronger backgrounds more warranted.
From "roleplay point of view" you absolutely can make interesting choices with different backgrounds and classes as it is.
But that's not what OP wants.
The point of the original post, how I understood it, is that currently a "warrior-background" does not give as much extra stuff to a "warrior" class, as a "not-warrior background". And in my opinion it is absolutely fine, even expected.
AFAIK the backgrounds are the ONLY way you can select abilities for starting with. It's somewhere inbetween flavour and utility.
That being the case, there should be a few more of them, with a few more, and different combinations. The suggestions above are good.
Just chiming in here with one of the reasons I posted this.
Taking "Martial" focused Backgrounds clearly adds value to non-martial classes who are often gated on things like Armor Proficiency or certain skills.
For example, I have been making all of my Shock Arcanists with the Sellsword background. It gives them Athletics (which is hard to get as a Wizard) and more importantly Medium Armor Proficiency, which is amazing for a Wizard.
Or for Lowlife, which is a nice way to build a Wizard and get some Rogue Utility proficiency, etc.
Just chiming in here with one of the reasons I posted this.
Taking "Martial" focused Backgrounds clearly adds value to non-martial classes who are often gated on things like Armor Proficiency or certain skills.
For example, I have been making all of my Shock Arcanists with the Sellsword background. It gives them Athletics (which is hard to get as a Wizard) and more importantly Medium Armor Proficiency, which is amazing for a Wizard.
Or for Lowlife, which is a nice way to build a Wizard and get some Rogue Utility proficiency, etc.
Sellsword is the new 1 level Hex Blade dip.
Its the new Mountain Dwarf Wizard but no downsides because you can still be a +1 int high elf.
Sellsword gives wizard light armor/medium armor proficiency which is too good now. And lawkeeper gives all martial weapon proficiency?! lol That is too broken.
Martial weapon proficiency isn’t a huge deal. You need str/dex to effectively use them and you need extra attack at level 5 to continue to use them effectively.
Without that a martial weapon is, in general +1 or +2 (ok up to +3.5) damage on a regular attack or an opportunity attack. Which is good, but isn’t going to wow a wizard or cleric
I'd like some kind of custom background option, or at least customize one or two of the background's skill proficiencies to be able to actually pick what skill proficiencies your character wants. The selection right now is already slim, and being unable to choose just hurts that more.