Chilvary is a form of honour.
However, in regards to Anytime, him fighting Dutch weaponless was the only chilvaric thing he did! Also, like you said he was playing with him and savouring the kill. However, I would like to think that he considered Dutch was some sort of challenge! Otherwise, why did he scan Dutch facial features prior to dropping all its weapons? Surely he saw something in Dutch that was worth a mele? Although, Dutch did get his ass kicked!
Also, I don't consider Predators as Space Samurais. I always hated this concept, read my original post!