Kingdom Come Deliverance: Hidden Perks?
As stated in comments already (but not as answers), these are hidden perks :
- Gathering 100 nettles will give you "Resistance", granting you a permanent +2 to Vitality
- Killing several dozens of Cumans will give you the "Cuman Slayer" perk, granting you a +50% bonus to moral damage versus Cumans (i.e. they are more likely to flee/surrender)
- Perfect Block/Master Strikes are taught by Captain Bernard at Rattay. You cannot get them in any other (normal) way.
- Having sex with a bath wench (ask a bathhouse propritary)/Theresa/Lady Stephany/after partying with Father Godwin (one quest for each of them, with sex at the end) will give you the "Alpha Male" buff, granting you a temporary +2 to Charisma for 24 or 48h.
Two quest related perks are missing from the other answer.
You get one Perk on the Quest "The Prey" where you go hunting with Hans Capon, the perk lets you loot game animals you kill without it counting as stolen so all the hares you kill while it's active you can keep and sell legally.
The second perk you get by completing a series of quests by the Huntsman of Talmberg which unlocks after the battle at Pribyslavitz, if you side with Hare you get the option at the end of the questline to become the Huntsman of Talmberg and get a perk with the name of "Henry the Master Huntsman", the perk like the previous one allows you to loot wild animals without it counting as stolen except it is now permanent.