There are 5 "armor" feats in PHB: Lightly/Moderately/Heavily Armored, Medium Armor Master, and Heavy Armor Master. Four of them add +1 Str, of those some allow +1 Dex instead; Medium Armor Master adds neither. I am considering that I let my player take the Medium Armor Master feat with +1 Str. Is that balanced?
I think it is, and my reasoning is as follows: Medium Armor Master adds two bonuses:
- no disadvantage to Stealth checks due to medium armor (some medium armor types impose that);
- Dexterity bonus to AC is capped at +3 instead of at +2.
Compare this to the Heavy Armor Master feat, which grants +1 Str and -3 reduction to received bludgeoning/slashing/piercing damage. -3 damage reduction is good but scales worse than +1 AC - that might explain why there is no +1 Str for Medium A.M. On the other hand, while that -3 damage reduction is immediately applicable to anyone, +1 AC requires and Stealth check assumes high Dex and +1 Str is of real use only to a Str-based fighter. So anyone wanting to use the modified Medium Armor Master feat to its full potential need to invest both into Str and Dex, which obviously costs other opportunities.
Is there a flaw in my reasoning and the modification indeed causes a disbalance?
The actual situation is that a Str-based Ranger in my group often serves as the group tank, and the initial build gave her Str 15; so the modification is a bit tailored for her. Other players will likely be fine with that, but that should not make the question irrelevant.