フレッドとジョージがケーキやら何やら、キッチンから失敬してきたんだ。 (Harry Potter (book 1) Japanese TL)
Fred and George have stolen cake and what have you from the kitchen.
I'm wondering what nuance 失敬する provides over 盗む in this sentence.
Given the context of the sentence and the fact that 失敬 also means 'impertinence', I'm guessing that 失敬する is more lighthearted, whereas 盗む would imply more of a criminal act. I can't find anything to back this theory up though.
失敬 is primarily recognized as one of the polite ways of saying "Excuse me" or "My apologies", and I see 失敬する as a verb version of it. It's much more euphemistic and "politer" than directly saying 盗む. I wouldn't go so far as to call it "the humble verb for 盗む", but it does have a nuance similar to humble verbs like いただく or 頂戴する.
失敬する can be used for completely criminal acts, but in such cases, it indeed might sound somewhat jocular or lighthearted. My mental image is a gentlemanly thief like Arsène Lupin.
I didn't even know the word 失敬する until I looked it up 2 seconds ago so take this as you may, but from looking it up I noticed one of the definitions is "taking without permission" which is a better definition for this example IMO. For example I wouldn't say Steve stole his moms credit card to buy LOL skins but he certainly used it without getting permission.
