The Scottish seamer has suffered a hamstring injury, ruling him out of the showcase occasion at Edgbaston
Josh Davey will miss Somerset's attempts to capture the T20 Blast title after being ruled out of Finals Day with a hamstring problem.
The 31-year-old right-arm seamer picked up the issue while playing in the quarter-final win over Derbyshire Falcons at Taunton, bowling just a single over in the 191-run success.
A Somerset statement adds Davey, who has taken 15 wickets in 11 Blast matches, will "undertake a tailored rehabilitation programme" to ensure he returns to full fitness.
The 2005 winners, who face Hampshire Hawks in the second semi-final at Edgbaston, are already without Craig Overton after he was retained by England ahead of the third one-day international against India at Old Trafford.
Leonard's development has taken a setback (Harry Trump/Getty Images)
The west country club will be without Ned Leonard for the rest of the season due to a stress fracture in his lower back.
Leonard made his senior debut in the One-Day Cup last summer, taking three wickets in four appearances, and has continued his development with a handful of outings for the second XI.
Working with the club's science & medicine department, he will undergo a "bespoke recovery programme" in the hope he can return ahead of the 2023 campaign.
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