So the trade-off with this perk is +3% Critical Hit Chance, faster movement, cheaper repairs (especially with Jury Rigging, almost everything can be used to repair Joshua Graham’s Armor) and this armor weighs 1/4th as much as Elite Riot Gear. The best Light Armor challenge to this is probably Joshua Graham’s Armor, which has a max Damage Threshold of 15 and a +3% Critical Hit Chance. An easy candidate for best armor in the game is the medium armor Elite Riot Gear, which has a max Damage Threshold of 22 and +5% Critical Hit Chance (among other bonuses which aren’t interesting). Of course, the issue here isn’t whether a +5% Critical Hit Chance is a good thing (it should be pretty uncontroversial) the real issue is whether Light Armor - with the aid of this perk - is worth anything. Sure, when you hit level 50 the reduction of critical hits will be eclipsed by whatever level 50 perk you pick… but the +5% Critical Hit Chance is still as good as Finesse.
This perk gives you a +5% Critical Hit Chance and imposes a -25% Critical Hit Chance on your foes while wearing Light Armor. While wearing light armor you gain a +5 Critical Hit Chance and your enemies suffer a -25% Critical Hit Chance. Heavy armor just isn’t your thing, so you’ve learned to customize light armor for maximum benefit.