It took only 8 years
, but it just occurred to me , that Sailaba may be another version of phonetic transliteration of "Selaava", the local name for what the Brits designated as "Khyber knife".
If that is correct, and taking into account frequent construction of the Khyber knife with a (slightly) recurved blade, we may finally understand where the term "Salawar yataghan" came from.