Etymology of Gr. SkutHe:s 'Scythian'

From: Sergejus Tarasovas
Message: 32990
Date: 2004-05-31

If Gr. _skútHe:s_ is a borrowing from an Iranian word etymologically
connected to Old Persian saka- 'Scythian, Saka' (< Proto-Iranian *saka- <
(?) PIE *k^ek(W)- 'achieve, be able'), one would assume sk- to represent the
zero-grade of *sak-, but what about -utH- of the Greek word? American
Heritage (s.v. Ashkenazi) quotes Old Persian sku:c^a- (sku:ca- or sku:ça- in
the standard notation?) but the word is not on the Kent's list and it's
unclear to me what that -u:c- (or -u:ç-) would mean etymologically anyway.