Board Thread:Questions and Answers/@comment-174.49.12.250-20151222215312/@comment-1173941-20151222223332

Hard to say. I would interpret the title as a reference to Yuuki's mother, who was a devout Catholic, so the "Rosario" in the title is probably referencing the set of prayers, or the set of beads of a rosary, used to count the components of the prayer.

An extended interpretation of this, could also mean that the 11 hits from Yuuki's 11-hit Sword Skill, Mother's Rosario, represent one decade of the rosary, plus the crucifix.

See the Wikipedia article on Rosary for details.

I'm no expert on Catholicism, and really don't know what the Author had in mind, but this is my best guess.