Thank you so much for posting this very attractive example Justin! That is a help, I didn't realize that the heart symbol appeared on the skean dubh.
An interesting note on the term skean dubh, which means in Gaelic 'black knife' literally, but actually the term dubh also meant 'dark'. In the case of the skean dubh dark =hidden, as these were hidden in the stocking while the rest of the Highlanders personal armoury was set aside in visits etc.
Brings to mind the 'hideout' pistols worn on the ankle in modern times
In some recent reading I discovered that the North European 'dusagge', the basket hilt sabres believed to have been used by Scottish mercenaries and often mistakenly termed 'Sinclair sabres' often had heart shaped cutouts in the guard panels. The same heart shape cutouts appear on some East European sabres in Austria/Hungary (Wagner notes these shapes may have reflected the work of gypsy smiths). In Polish armour of the 17th century these heart shape cutouts are also seen, and it seems that I saw this in some examples of Polish Winged Hussar armour.
All admittedly speculative association, which I tried to follow through on many years ago ,and communicated with Professor Zygulski, who wrote on the Polish Hussars, as well as with Claude Blair concerning heart shapes in Scottish basket hilts.Both considered the possible connection interesting, but of course unproven.
I also communicated with Dr.Mazansky as he was writing his outstanding book on British basket hilt swords, but he emphasized his study was focused on typology and not much on symbolism in the hilts.
I thought it would be interesting to revive this inconclusive idea here, as I think the symbolism found in these weapons most intriguing.