A welding system comprises pieces positioned to form a gap, a filler positioned in the gap, an arc welder positioned and configured to follow the gap and transfer melted material to the vicinity of the gap to create an initial weld pool, and a laser welder positioned and configured to project a beam through the initial weld pool adjacent to the gap to melt a portion of the filler, creating an enhanced weld pool and helping it to fill the gap. A welding method comprises fixing pieces to define a gap, positioning a filler in the gap, applying an electrical arc to at least one of the pieces so as to transfer melted material to the vicinity of the gap and thereby create an initial weld pool, and projecting a laser beam through the initial weld pool adjacent to the gap to melt a portion of the filler.