A weak Reimu who needs the spellcard system as much as the youkai do to make fighting actually possible (and thus continue existing by making a game of it all) is interesting, but also it's really funny that the youkai everyone always uses to show off how dangerous and scary youkai really are is just always Rumia. This little clown who bonks into trees because she can't even see where she's going half the time.
Yeah she's the danger, because she really is.