She usually says the phrase "how shallow-minded" (あさはかなり,asahaka nari). Is the fact that she came from the past (a.e Feudal Japan) and was born in Ancient Japan has something to do with it?
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2The suffix -なり is an ancient word. The repeated usage of the phrase suggests that she is from the past. – Pteromys Dec 27 '13 at 14:05
As stated in the wiki page you linked to, it's most likely because she's from an earlier era.
Also, being a trained assassin, she most likely views the actions of other characters as childish and foolish, so she just gives her honest opinion on the matter.