If it's never come up, I'm not a huge fan of the default combat style traits in Mythras, since the effect of most of them is to make you ignore a cap on your combat style in some situation. e.g. When you're riding a horse in combat, your Ride skill "caps" (determines the maximum percentile value of) your combat style - unless you have Mounted Combat, in which case you get to use your full combat style.
Rules-as-written, a combat style trait only grants one benefit, and you can only have one trait per combat style, but this seems to be
something honoured in its breach in fan-made material (Shout out to the
Notes on Pavis guy for running a great blog). My assumption is that this represents running up against the limits of how this works in actual play, since it's something I've run into as well.
To recap the situation with combat styles in Mythras: The average Mythras character has 1 or 2 combat styles to start, and perhaps learns 3-4 total over the course of a long career. These combat styles form the primary skills characters use in combat for both attack and defense, and thus are a priority for most characters to boost. Those 1-2 additional combat styles will primarily be driven by either the traits of a new combat style, or the need to shift the weapons they use (or some combination of these two).
With the typical split between combat and non-combat characters in the parties I've seen (about half of all characters being combat-focused, meaning they get two styles), assume a starting party has about 1.5 combat styles per party member, except these aren't unique styles - most characters have a single cultural style common to all of members of that culture, and most Mythras parties are from a common cultural background. So only the 0.5 extra combat styles per PC are actually unusual or unique ones. In a party of four characters of shared background, that means you'll have one common style, and two unusual ones, each accessed by only a single PC.
How many combat styles there are in a particular setting varies widely, but typically you have between 3-6 per culture, depending a lot on military specialisations available within that culture. Most Mythras settings only use a small subset of the giant list of weapons included in the Mythras corebook - between 6-10 is typical, with 3-4 weapons per combat style, and in practice, you see a lot of repetition of the best weapons in different styles (Hello shortspear my old friend).
What this means in practice is that a lot of the odder combat style traits tend not to appear - they're either not attached to the main 3-6 options available, or they're just not present among the 3 different combat styles in a 4-person party (if you run with six PCs, you'll end up with 4 different combat styles on average). Also, some of the traits are far better than others because the combat situations they apply to are far more common, and these traits tend to be the most common, repeating across combat styles.
One of the outcomes of all of this is that combat style traits are not actually a very good method to ensure PC combat styles aren't capped. I'd rather just not have the caps in the first place, since they tend to take exciting action combats where the PCs are doing things like chasing people around on horses or climbing the rigging of a ship or storming a castle's walls and turn them into frustrating whiff-fests. Realism be damned, this is a game where you can play a cat-man wizard, and that cat-man wizard should be able to stab a guy while swinging from the rafters.
In place of the current combat style traits then, I propose that caps should be abolished in most cases, and combat style traits should not be the mechanism by which they are nullified. Instead, combat traits should focus on empowering characters with options or intensifying their combat advantages.
Here are some proposed new combat style traits. Each one has several abilities it grants to someone trained in a combat style, and most a couple of regular combat style traits cobbled together.
BerserkerAllows the use of the Flurry special effect so long as the character is wielding two weapons and the extra attack uses the second weapon.
If a character's damage modifier is two steps higher than an opponent's, their weapon size is considered one step larger for the purposes of bypassing parries.
Any psychological resistance rolls by an opponent are one step harder.
DuelistMay use Evade to dodge attacks in melee combat without going prone.
Allows use of the Flurry special effect so long as all extra attacks are made with a single weapon.
Can use the Change Range action to automatically withdraw from combat without a roll.
LancerMaking a mounted charge with this style does not incur the one-step penalty to hit.
A character may spend action points to defend against attacks targeting their mount.
A character's damage modifier counts as one step higher for the purposes of calculating knockback.
Line InfantryIf three or more characters with this trait are in close order with one another, then:
Any enemy who engages them has their action points reduced by one.
They automatically get the benefits of using the Brace action against Knockback, Leap Attacks and Bash attacks.
Each character can ward an additional location using a shield or secondary weapon.
MarksmanA character may make ranged attacks while running (but not sprinting).
When using a ranged weapon, the hit location of a successful attack may be shifted to an adjacent location.
If three characters with the Marksman trait attack a single target or group of targets in close order, the targets are automatically Pinned Down (per the special effect).
Mounted ArcherA character may make ranged attacks while their mount is running (but not galloping).
When using a ranged weapon, the hit location of a successful attack may be shifted to an adjacent location.
A character can evade attacks without going prone while mounted, using their Ride skill in place of Evade.
Self-DefenseCan use the Change Range action to automatically withdraw from combat without a roll.
A character increase the size of your weapon by one step while parrying so long as they don't attack that round.
Outmaneuver rolls are one step easier.
Stalker
Can use the Kill Silently special effect.
When using a ranged weapon, the hit location of a successful attack may be shifted to an adjacent location.
Opponent's rolls to outmaneuver an attacker using a combat style with Stalker are one step harder.
WrestlerCan use Grip as a defensive special effect
Opponent's rolls to evade, break free of, or resist immobilisation in a grapple are one step harder.
Unarmed blocks and parries count as "medium" sized.
Because the average character has only 1-2 combat styles, adding a couple of extra conditions or abilities onto each combat style trait doesn't increase the complexity very much for any given player. Monsters and most opponents don't even have combat style traits, so while the occasional custom-built major villain will have a touch more complexity due to this, most opponents won't be any harder to run for the referee.
You can make combat style traits that require 3 or more characters to get their full benefits available as cultural styles, so that most of the party will end up with them.
If you don't want to get rid of caps, then I would suggest at the very least combining a no-cap combat style trait with at least one other combat style trait that does something interesting.
I haven't play-tested these yet, but I'm hoping to later this year when I start up a Dawnlands campaign.