What the plural of sgian dubh?

[JonathanB]

After I'd started this I thought how does one say the plurals in English of foreign words that would not end in "s" in their original.

In Italian, the plural of pizza is pizze.

In English to say "There's a choice of different pizze" would sound affected, if not incomprehensible. "There's a choice of pizzas" is the only possible way to say it.

I'd put the "s" at the end of sgian, rather the dubh.