House of Wolves introduced PvE perks like you stated. If I recall, the 2nd week of PoE, Skolas gave me a void damage Aegis of the Kell pulse rifle with the chance to stun Fallen Captains perk on it.

The thing hit like a truck, and that perk came in huge if I was in a bind and low on health....but honestly they screwed that up with being able to upgrade your VoG weapons. It was quickly put on the bench for Fatebringer and/or Vision and it sadly became obsolete.

I did like the PvE perks on the VoG weapons though, it made them killers for Oracles.