Venting because I just spent half an hour trying to figure out what 当たるを幸い meant, because the phrase by itself was just so grammatically wrong and made no sense to me (it uses a verb 当たる as a noun without a nominalizer). Evidently, the Japanese have idiomatic phrases for other idiomatic phrases. Idiom-ception! Thank you, Japan.
…thank god for Google-sensei T^T