Steven Davis knows what it takes to defeat Celtic in an Old Firm cup final. Whilst the legendary Rangers Hall of Famer was only 17-years-old the last time these two teams met in a Scottish Cup showpiece, Davo scored in the 2-1 Hampden League Cup win of 2011. It’s just one moment from the highlight reel of big Rangers goals belonging to Steven Davis, whose presence on the pitch at Ibrox has been sorely missed. Now, after officially hanging up his boots, the Rangers legend has been singling out one star who he believes can play a crucial role against Celtic at Hampden. READ MORE: Rangers star gi…