See one of my favorite Rivendell headcanons is that even though it's a wonderful, peaceful sanctuary, pretty much everyone there could be incredibly dangerous if they wanted to be. Like, let's think about who lives in that valley.
Elrond Peredhel, resident healer and eldritch crime against nature, self-explanatory
Glorfindel, slayer of balrogs, self-explanatory
Erestor, probably Feanorian, definitely dangerous
Old Feanorian diehards, all of whom are probably looking for an excuse to commit morally justified violence
Old Gondolindrim/Iathrim, who, despite what they might tell you, are exactly as dangerous as the Feanorians
Garthaglir the Library Orc, who absolutely remembers how to use the giant battleaxe he keeps behind his desk
A strange, shadowy figure roaming the valley who I'm *sure* isn't Maglor Feanorian, but who is nonetheless a terrifying singer
Elladan and Elrohir, who have spent the last several centuries becoming nightmare fuel for Sauron's forces
Bilbo Baggins, not to be underestimated, can defeat a grown man with nothing more than his scathingly polite commentary
Dunedain visitors, vaguely feral, highly trained
Aragorn, very feral, highly trained
Lindir, not actually dangerous, but if you upset him you are going to have problems with everyone else on this list
I actually really like the idea that a lot of the people who live in Rivendell are inherently kind of dangerous, because it means that they're actively choosing peace and kindness for themselves and I love that.