Arabian Mate

fen: k7/5p2/1RNp2p1/2P5/2K2b2/8/r7/8 w - - 4 4
id: PSY1xiy5

knight guards the rook and the escape square

Balestra Mate

fen: 8/pp4pk/8/3pQp1p/4bR2/1P2P1q1/PB6/6K1 w - - 0 1
id: 526D7K_o

when the queen is off to the side like this (one knight's jump away), the enemy king can only move on the opposite color squares. So a bishop is perfect for delivering mate. Notice we also adopt this strategy to drive a king to the edge of the board in queen vs king endgames, because this "knight's jump" distance covers so many squares