Heat grill to high (see page 367 for instructions); lightly oil grates.
Cut swordfish and salmon into 24 pieces each (about 1 1/2 inches); dividing evenly, thread fish against the grain on 8 skewers, alternating with cherry tomatoes.
Brush bread slices on both sides with olive oil, and grill until lightly charred, about 2 minutes per side.
In a blender, puree basil, garlic, and the olive oil until smooth; season with salt and pepper.
Reserve half.
Brush kebabs with basil oil; season with salt and pepper.
Grill, turning occasionally, until fish is opaque throughout and tomatoes are softened, 6 to 10 minutes.
With a clean brush, coat kebabs with reserved basil oil.