مَعَ جَوَازِ أَنْ يُرَادَ حَقِيقَةُ طُولِ النِّجَادِ أَيْضًا
The actual length of the sword strap may also be intended.
A tall person may genuinely have a long sword strap. The expressed statement may then be literally appropriate as well as indirectly conveying the person's height. That is a clear case of the permissibility of the literal sense.
Yet the conventional allusion can still communicate tallness when the person does not in fact wear a sword. The definition does not require the literal circumstance to exist in every use; it requires that the kind of expression does not rule it out by its nature.