Then that breaks the premise of your situation. If Data has a 17 minutes to prepare and a regular 24c phaser and he's aware of what the T-X can do and is capable of and he knows this is a "fight to the death" then why wouldn't he put the phaser on one of it's higher, more disruptive, settings?
Because in a straight fight Data wouldn't have a chance. Falls, electrical arcs, and dimensional portals have all taken out Data or his limbs through the series. A regular 16th century arrow was even able to cause superficial damage to Data. The T-X with the various weapons built into her endoskeleton would be able to make pretty short work of Data who only has a phaser, apparently, only set to "kill" which isn't going to do squat to even a T-800, let alone a T-X.