[RPG] Class armor proficiency vs. armor proficiency feats

It’s very difficult to prove a negative, but I am reasonably confident that no rule in 3.5 or Pathfinder explicitly states that all armors of a given weight class slow you down by the same amount. In 3.5, at least, there were certainly a few super-heavy armors that reduced the speed by more than your typical heavy armor (Races of Stone had a couple of these).

So yes, every Medium or Heavy armor must somehow explicitly state its own speed reduction, even if the overwhelming majority of them have the same speed reduction. On the other hand, if a given case failed to do so, I’d just chalk that up to the designers not realizing there was no such general rule, since it usually is so consistent and armors which slow people more or less than others in their category are quite rare. It’s also worth keeping in mind that it is consistently weight category that we should consider, not sheer weight.

According to D&D 5e designer Mike Mearls, the Mountain Dwarf is only proficient with light and medium armor and not proficient with shields.¹

In RAW, if you want shield proficiency, you either need to pick up a level in a class with the proficiency or take the (optional) Moderately Armored feat, as no other feat grants shield proficiency.

I would highlight Mountain Dwarves are the only (sub)race that get any kind of armor proficiency. However, this is not totally redundant since the Mountain Dwarf subrace needs only one feat to gain shield proficiency (Moderately Armored) while all other character races need two (Lightly Armored and Moderately Armored). The designers may have felt two full feats, in addition to the other (sub)racial benefits, to be too much for the Mountain Dwarf,¹ although it's somewhat ironic that so-called "shield dwarves" in Faerûn are not racially proficient with shields.

DMs may also house rule that other armor-related feats, such as Medium Armor Master, Heavily Armored or Shield Master, grant shield proficiency. In another apparent contradiction, the Shield Master feat (PHB, p. 170) neither prerequires nor grants proficiency with shields.

1. In a tweet exchange on November 2, 2014, @RichardMassive asked:

   @mikemearls in the PHB things that give medium armor prof also give shields, with one exception: the Mountain Dwarf. oversight or intended?

   Mearls responded:

   @RichardMassive intended - shields are a little too flexible to give out as easily.