Vermintide 2's deed system was originally conceived as a way to offer players an additional challenge, as well to make things more interesting by tweaking the usual gameplay formula. Unfortunately, deeds as a whole ended up being a bit of a disappointment. The rewards were rarely worth the effort, most of the mutators were boring or simply didn't offer enough of a challenge, and most problematic of all, you could only receive deeds through random chance.
With that in mind, I am very glad to say that Fatshark has now decided to give the concept another chance through the newly introduced Weekly Events. While the full list of events has not yet been announced, the very first one has been a resounding success so far. Basically, every time you kill an enemy, two weaker enemies will spawn in their place. And yes, this does include bosses! So if you're like me and you love cleaving through hordes upon hordes of enemies, this event is well worth checking out!
On a completely unrelated note, the picture frames that have been conspicuously empty since release can now finally be filled with a variety of paintings. Naturally, the fancy paintings won't be given to you for free, but don't worry as you won't have to whip out your wallet in order to acquire them. Instead, each level has now been populated with scraps of ravaged art, and if you manage to collect enough pieces you will be granted a brand new painting to toy around with. A simple enough system, but given how devious the Vermintide 2 devs can be, I wouldn't count on the scraps being easy to find! After all, the journey is half of the fun.
You can learn more about this update, as well as check out the various balance changes, over at the Steam forums. Have fun and happy hunting!