For the life of me, I can't think of a single small/weak realm that Sirion wiped out. (Although I've only been playing for 7 years, there may have been some before that.) Now, Sirion has wiped out a few realms, but they didn't qualify as small/weak when the war started.
Avamar and Eleador comes to mind. The latter was an ally of Sirion but yet they died by Sirionite hand.