Specularity can be caused by the relative size of the light source, by the type of modifier, but also by the ANGLE of the light as it strikes the subject...light that "glances" onto a human can be very hot, and very specular if it hits the subject at a glancing angle.
On human skin: a light at 8,9,or 10 o'clock in relation to the skin is "soft" to "normal" in its degree of specularity.
The SAME light (and I mean the exact, same light, at the power,same distance,with the same modifier), glancing in from a steepish angle, such as with the light placed at 11,12,or 1 o'clock in relation to the subject, will be VERY hot; same with the light passed behind the subject and located at 2 or 3 o'clock.
This is an unusual effect: the readings from a light meter will be 'the same', but the actual angle a hair-light, or rim-light, or accent light is placed, will determine if the light is rendered in a normal way, or rendered as very "hot" or "harsh".
The typical hair-light, or accent-light, or rim-light can be placed behind a person, at say 11 o'clock on their left, or 1 o'clock on their right, and only a very tiny little squirt of light can create a pretty "hot" bit of light; but id the same,exact light amount comes in from say, directly left or right, at 9 o'clock or 3 o'clock, and hits them "square" on one side, the effect will NOT be "hot" to nearly the same degree. Odd, but true. This is one time when you can NOT really trust a light meter.