Intimidation/Instill doubt gone?
 

Hey everyone I'm a rogue, and last time I played was about two years ago, and at that time I had the intimidation skill on my hotbar. The skill actually still shows there, but when I hit it, nothing happens. I looked in my skill list, and I see neither this nor instill doubt are in my skill book. Did something get changed in regards to those skills?

Its still in the game, when you go to intimidate a mob you'll likely see "You're not scaring anyone".

Try resetting your UI if its something else.

It's definitely still in game as I was fear kiting in DL just last night on my rogue.

Swish's suggestion is a good one.