I didn't say anything about something greater than Pride, but Arrogance is certainly a form of Pride and interviews about the Elder One have certainly emphasized his arrogance to the point of calling him arrogance rather than merely arrogant.
Consider the level of power and manipulation I don't think we are dealing with a pride demon of any kind since that seems way beyond they are cable off.
It must be something bigger and more powerful then anything we have encountered before.
It's probably bigger and more powerful than any other Pride Demon we've seen, and also much, much older. It likely has a unique set of experiences and knows more about things than most Demons.
Chances are that it recalls a time before the Veil and seeks a return to that time.
Him being just a Pride Demon doesn't necessarily take much away from how much of a Pride Demon he can be. The Architect and Corypheus are just Darkspawn. Special Darkspawn, but still just Darkspawn.
The way the Elder One is described, he seems defined by his arrogance. That makes it sound like he's either an Arrogance Demon or an Arrogance Abomination of some sort, however ancient and unique he might be.