In Supernatural season 12 episode 13- Family Feud- we see Dagon kill two angels. However, it didn't seem clear to me whether she was holding something in her hand when she killed the two angels, or whether she can straight on kill them with her bare hands. There was a youtube video which seemed to show her holding something in her fist if you played it in slow motion, but it's no longer there.
Another reason I thought this (which isn't exactly direct evidence), is that demons have never had the power to directly kill angels without a weapon, even very powerful ones. We see Ramiel having to use the Lance of Michael in order to fatally harm Castiel for example.