Moved the thread under Bug Report, please use the correct subforum next time.
Plated Leather Set works fine, I just tested it.
Samurai Longsword: Critical Damage does not work and will be fixed after next restart.
Sword of Damascus: Critical Damage does not work and will be fixed after next restart.
Salamander Skin Mail does not give a set bonus, you can read the description of the item.
Edit: Also fixed the following item Special Abilities: