The “weaver’s knot” is a Society invention; while weavers certainly used knots in period, we’ve no evidence of this knot being particularly associated with weaving, and no period heraldic examples have been adduced. Pending documentation, the weaver’s knot has been disallowed for Society use.
Margaret Johanna van Artevelde bears: Per pale potenty argent and vert, in bend a weaver’s knot sable and a woad plant Or, stalked and leaved argent.