A hand-held device for joining fishing line segments of monofilament, fluorocarbon, and/or braid lines of similar or differing sizes or combinations. The device is electrically powered and is portable. The device includes an encasement for orienting the fishing line segments in a closed chamber in close, tensioned, non-contacting orientation. A material is injected into the closed chamber to encase the lines. This material can be adhesive material or a flowable polymer material having, typically, a melting temperature lower than the line segments to be bonded. Alternatively, A pre-formed, flexible polymer sheath (or sleeve) is used to retain the line segments in the chamber. A heater heats the polymer sheath (or sleeve) within the encasement to allow the polymer to flow and encase the line segments without melting the line segments. Bonding of the line segments can be achieved without melting, abrading, compressing, or impairing the integrity the line segment (s) to be encased. The result is a system that is able to join various types and sizes of fishing line segments together or securing hooks or other components to at least one line.