Quote Originally Posted by Kane0 View Post
You could change the prohibition to be against metal armor kinda like druids? What is it about medium armor and shields that are so bad you want to avoid?
Slayers are trying to die. They charge into battle bare-chested, with an axe in each hand or a double-bladed greataxe in both, hoping that a sufficiently valiant death will absolve them of their disgrace. Honestly, it's not unlike the druids' own prohibition, which has always struck me as weird among 5e rules.
From the Career Compendium for Warhammer Fantasy Roleplay, 2nd edition:
Spoiler: A Troll Slayer's Leather Jerkin
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When slayers form regiments in dwarf armies, they are famed for fighting bare-chested, showing their brethren that they will meet their doom with gusto. So it can strike some people as remarkable that Slayers are found wearing leather jerkins. Surely they wouldn’t seek to protect themselves?
The fact is that leather jerkins are considered a practical comfort, rather than serious protection (dwarfs consider nothing less than a heavy mail coat to be serious protection). Only hard-wearing gear will survive the wilderness wandering a slayer undertakes. The famous bared chest is something of an affectation of the battlefield.
So it is not uncommon to see a troll slayer wearing a leather jerkin, and no hypocrisy or cowardice should be inferred by the fact. Many slayers arrive to fight, shed their travelling gear (jerkin and all) and charge in to face their doom with torso bared.

As for what else to put at 14th level (or elsewhere), I have a few ideas:
  • If you have no more than half of your hit points left, you have resistance to acid, cold, fire, force, lightning, necrotic, poison, psychic, radiant, and thunder damage. (I might want some tankiness after all; while raging, this gives you resistance to all damage.)
  • Whenever you take the Attack action while raging, you can attack three times, rather than twice, if you are outnumbered or fighting an opponent larger than you, or four times if you are both. ("I have you surrounded...from the inside!")
  • You gain proficiency with a tool of your choice. (Slayers often work odd jobs in between monster fights.)
  • When you attempt to tattoo or adorn yourself, you are considered proficient with jeweler's tools and painter's tools. (Slayers are easy to spot.)
  • You may add half your proficiency bonus (rounded up) to any Constitution check you make to drink or resist the effects of alcohol. (Warhammer challenges you, character and player, to keep your sense of humor.)
  • When you have 0 hit points, you can choose to die, rather than make death saves. When you die, all of your allies that can see or hear you gain advantage on all attack rolls, ability checks, and saving throws until the end of their next turn. They automatically succeed on any ability checks to recall how you died, or to recount the tale to others.

If I were to throw out Slayer's Quarry entirely, I could double the Rage Damage against Large or larger creatures at 3rd level, triple it against Huge or larger creatures at 6th level, and quadruple it against Gargantuan creatures at 14th level.