>>52323
>Don't perks give boosts to only heavy or light armours?
Juggernaut gives boosts only to heavy armor, yes. Agility applies to both light and medium (medium gets less benefit) though, and Unhindered depends on the defense stat and not the type (there's even heavy armor that can potentially benefit from Unhindered).
>Is there a point to using medium armours?
Like >>52324 said the main point is aesthetics, but there can be mechanical reasons to go with a medium armor. It depends on what perks you have and what your armor options are. There are very few medium armors in the game, so I'll just go over all of them.
>Skimpy Armor
>Chainmail
Probably the first medium armors you'll find, and they should be compared with the other choices in Tel'Adre's shops, because all the armors for sale in Tel'Adre are inferior to the stuff you can craft.
The point of skimpy armor is the tease bonus, and the main alternative for that is the chain bikini (light). Both of them should have no problem activating Unhindered, skimpy armor has better tease bonuses (though the difference is tiny) and better defense (unless you have the Agility perk and 80+ speed). Since this is just a temporary armor until you can get something better, there's a good chance you don't have the speed/perk to make the chain bikini stronger, making skimpy armor the better choice. If you do have the perk/speed, they're still pretty close, and it's a choice between a tiny bit better defense or a tiny bit better tease.
Chainmail is just bad. There's no mechanical reason to ever use chainmail.
>Dragonscale Armor
Dragonscale and spidersilk is avilable at around the same time, and probably a while before ebonweave, so your choice in this case is basically between the scale/silk options. Both types offer robes (light) with spell cost reduction and you can get inquisitor's stuff around this time too, so those are the obvious choices for mages. If you have Juggernaut, dragonscale armor doesn't offer any advantage over spider-silk armor (heavy) or store-bought platemail. But if you have Agility and normally go with light armor, then dragonscale will likely be the strongest defensive choice. With 100 speed it has the best defense of all the scale/silk options, and better than anything in stores. So even though it's medium, for a portion of the game it's likely to be the best choice for light armor users who aren't mages (unless you go for a dodge build, because dragonscale armor can't activate Unhindered).
>Ebonweave Jacket
>Ebonweave Robes
Ebonweave has four choices, one light, two medium, and one heavy. The robes (medium) and indecent robes (light) have a higher spellcost reduction, and the indecent robes have tease bonuses. If you have the Agility perk then the indecent robes also have better armor. The normal robes are only (mechanically) worth choosing over indecent if you don't have any armor perks and don't use tease.
The jacket (medium) and ebonweave platemail (heavy) both have the same spellcost reduction. The jacket has the same defense as dragonscale armor, but the platemail's defense is slightly better than spidersilk armor, so it's not quite the same choice as before. Obviously if you have Juggernaut you go with heavy. If you have Agility, jacket matches platemail at 115 speed, and surpasses it at 125. So it's hard to get enough speed for medium to be the better choice, but not hard to get enough speed to make them identical. And even with the higher Agility bonus for light, the ebonweave robes won't match up to the jacket until 175 speed, which isn't very realistic.
In short: If you have Agility and not Juggernaut, and you aren't going for dodge/lust/mage builds, medium generally ends up being a better choice than light. But in that case you're using armor mainly for the defense stat, and that's heavy armor's strength, so taking Juggernaut and wearing heavy armor would probably be better (if you already took Agility earlier though, you might have better things to spend perk points on than Juggernaut).