some perks only work with certain weapon categories for balance reasons and to focus certain specializations on certain roles.

Some perk descriptions have their localization (text) set up in a way that automatically inserts the weapon type they are currently carrying in the assigned slot (primary/secondary). Unless specifically stated otherwise, most shooty perks should work with all types of firearms. If you find one that doesn't, please report it in the Bug Reports thread.

Originally posted by bstar:

Some perk descriptions have their localization (text) set up in a way that automatically inserts the weapon type they are currently carrying in the assigned slot (primary/secondary). Unless specifically stated otherwise, most shooty perks should work with all types of firearms. If you find one that doesn't, please report it in the Bug Reports thread.

Thanks!. I will equip diferent weapon and see if anything changes in the description!

@wened You'll also run into situations if you use various mod-added weapons where a perk desc will say something like "Allows soldier to fire their "weapon_has_no_FriendlyName!" until all enemies die." (Example)

It's not a bug per se, it's a lack of a line similar to "bFriendlyName=[insert weapon name here]". Don't quote me on that, I'm going off of memory, but what I'm getting at is that missing FriendlyName messages shouldn't cause problems, they just mean the author left out a non-critical detail. Off the top of my head, the Clean TLP Weapons With Visible Upgrades mod causes this, and I know there are plenty of other weapon mods out there with the same thing. I keep meaning to go into the files and add friendlynames myself but I always forget.