A supplementary beater used with a handloom for constructing a fabric weave, and an associated method of use thereof. The handloom includes a warp beam, a harness for supporting and controlling warp threads, a reed defining a shed and disposed adjacent to the harness for supporting warp threads, and a shuttle for passing weft threads, one at a time, into the shed. The supplementary beater is adapted for manual insertion into the shed and for the purpose of providing an undulating weft pattern in the fabric weave.