"Sparing the second split was crucial and when I struck in the tenth, it must have put pressure on my opponent. This is also my first international title after been to so many and I'm really looking forward to win more."
Koivuniemi had earlier edged defending champion and third-seed, Osku Palermaa 238-228 in an all-Finn semi-final match to earn a chance to claim a back-to-back title after winning the Kingdom of Bahrain Open last week.
Palermaa sailed past winner of the first match and fourth-seed, Sandra Andersson of Sweden, 279-176 to set up the match with his compatriot, Koivuniemi. Andersson ousted fifth-seed, Ronnie Russell of USA, 226-185 in the first stepladder match to advance.
Rash picked up the top prize of US$25,000 and 50 World Bowling Tour ranking points and Koivuniemi settled for US$12,000 as first runner-up. Palermaa earned US$8,000 for finishing third while Andersson and Russell took home US$6,000 and US$5,000 respectively.