To a Welshman such as myself, Rhys is just a name - Rees.And pronounced in the same way as the English Rees.
In the Anglicised industrialased South Wales, it sounds the same. No h, and the y is ee.
North Walians will retain the h - Rhees.
Several Welsh rulers have borne this name.This I know, but the books tell me:
A male given name used in Wales since the Middle Ages.
From Old Welsh Rīs “ardour, fiery warrior”,and less poetically, simply "enthusiasm".
English equivalent REES
VARIANTS: Reece, Rees, Reese
In classical Sanskrit therefore, the transliteration is rīs and the Devanagari रीस्.
As just a word, rīs means to hurt, etc. injure, which I suppose is what warriors actually do, really.
However, some things can get lost in the translation, and the word can turn out to be quite rude to the ear of native speakers.
So better to ask them first.