大胆 can mean bold, daring or audacious, while 小心 means timid or cowardly. In effect, this likely means Marisa is timid at heart, but wears a bold/daring mask.
unicode said: I really think 小心 should mean "careful" here.
That would make sense. Marisa is bold, but she's also hard-working and, despite canon, quite deliberate and thoughtful about how she does things -- just not so much about what she does.
The Witch of Contrasts? Has some Umineko ring to it...
Has this been happening a lot?Weird.I don't know who it is, though.Hunh?Bold, Timid Human
Kirisame MarisaEh, someone keeps offering weird stuff to the shrine.Freewheeling Human
Hakurei ReimuIt always happens while I'm not watching.There's been a lot of sake offered, though.Yeah.Weird, but convenient.