SOLVED. Assassin-type fantasy, Author initials are J.S. [s]

[Elizabeth]

Was recommended to me today - at least 5 books. Apparently the fight scenes are done very well, with swordsmanship based on real martial arts. By someone whose name is Josh or something like that, his surname starts with S. The covers are mostly white with a band of colour, the titles are mostly (or all) one-word and written in a gold swirly font. I think the 3rd book has a red band and the title starts with P.

[Adele]

There's the A Trial of Blood and Steel series by Joel Shepherd.

First book:

Second book:

Third book:

[Elizabeth]

Bingo! Time to move to solved :)