Chaucer's harpist

In Chaucer's Troilus and Criseyde, there is this description of a harpist (Book II lines 1030-1036):

For though the beste harpour upon lyve 
Wolde on the beste souned Ioly harpe
That ever was, with alle his fingres fyve,
Touche ay o streng, or ay o werbul harpe,
Were his nayles poynted never so sharpe,
It shulde maken every wight to dulle,
To here his glee, and of his strokes fulle.

The context is Troilus being advised not to be too repetitive in writing a love letter: touching always one string or always harping the same tune would dull the listeners' wits. no matter how good the harp or harpist.

But the details are interesting. Using "all fingers five" is almost never done in any current style of harp playing (the only exception I have encountered is damping with the little finger in one of the Robert ap Huw motifs). Was it more common in the 14th century, or is Chaucer just not a very close observer of harp players? This could explain confusion over four vs. five fingers, but the "nayles pointed" is unlikely to be pure invention. Pointed nails are needed for nail plucking technique, which these days particularly associated with the wire-strung clarsach, but sometimes used on gut or other strings. Was nail technique more standard then, or could Chaucer in England have seen the Irish/Scottish clarsach played enough to have that impression of how the 'best harper' would play?