pickled sardines; dried sardines
Refers to sardines that have been preserved by pickling or drying, often with a reddish color. The literal meaning is 'red sardines'.
I served pickled sardines as a snack with sake.
rusty and blunt sword
Figurative use comparing a neglected, rusted sword to the reddish color of dried sardines. Rare and somewhat poetic.
The old sword was rusted like a red sardine.
Mixed kanji-kana spelling; usually written in kana.
Full kanji spelling; rarely used and may be unfamiliar to many readers.
Compound of 赤 (aka, 'red') and 鰯 (iwashi, 'sardine'). The figurative sense for a rusty sword comes from the reddish rust resembling the color of dried sardines.