Weston fell 10 runs short of victory at Downend, leaving the Seasiders three points short of safety.
Uphill Castle ended the season on a high note, beating Bishops Lydeard and finishing in third position in the league.
Weston seconds’ slim hopes of avoiding relegation were extinguished by fellow strugglers Keynsham.
Uphill Castle Strugglers made it three wins in four years at the club’s Big Bash event.
League champions Lympsham ended their season on a disappointing note, losing to Frome by five wickets.