むさしあぶみであれば
武蔵鐙であれば
musashiabumideareba

Noun
Da Copula

The "-eba" conditional form ("if/when…") of むさしあぶみ

1. If it were the Musashi-tōrō.; If the Musashi-tōrō existed.

Ba Conditional
Usually Written in Kana