I'd say it's both, and you need to make both rolls. In the situation in question Wesley was first trying to get Humperdink to believe that he could, in fact, fight him, should that be necessary. Subsequently, after providing sufficient proof that he might not be lying (standing up and raising his sword), he intimidated Humperdink into dropping his sword. Were I to GM a situation like that, I'd absolutely have the PC make the Bluff check first, and then if that roll succeeded make the Intimidate check. If the Bluff didn't go, no need for the Intimidate.
I have found when using a ploy or action that involves two different skills that you use the one with the highest ending bonus and lower the difficulty of the oppsed roll buy one for ever 5 trainnings you have in the other related skill.
say you have intimidation as a class skill with 5 trainnings and a 10 char you have a plus 8
say also that you have bluff as a non class skill but you have 5 trainnings in that as well giving you a plus 5
As a DM I would have you roll your intimidation dc 10 + target hd + target wis mod - 1 (for the 5 trainnings in bluff).
Or Have you roll an opposed Bluff roll against the targets since motive giving the target a -1 for your 5 trainnings in intimidation.
I would chose witch one by what seemed more favorable to the player (choice one)as a dm is not playing against the pc hes telling your story.
And that successful Bluff would likely add a circumstance bonus to the Intimidate.
Yes.