England will now head into the semi-finals on the back of a sixth straight victory, while West Indies will return home.
Tammy Beaumont made a resolute 42 as she helped rebuild the England innings alongside Knight.
Laura Marsh, batting at number nine, chipped in with a valuable unbeaten 31 while veteran Jenny Gunn scored 24 not out.
Sciver made amends for not contributing with the ball by taking two wickets in three balls, as Beaumont took an excellent sliding catch in the deep to see off Chedean Nation before wicket-keeper Aguilleira became the fourth player to be dismissed leg before wicket.
The hosts meet the Proteas at Bristol as they fight over a spot in the prestigious Lord's final, with England holding the psychological upper hand following a 68-run victory in the group game between the sides.
Already eliminated after losing their opening four games, West Indies entered their contest playing for pride but once again let themselves down with ordinary cricket - especially over the second half of the game.
But Gunn and Marsh finished with a flourish by sharing the highest partnership of the innings, putting on one more run that Beaumont and Lauren Winfield (11) had for the first wicket - Gunn also hitting the only six of her side's knock, off Taylor.
Wicketkeeper Sarah Taylor was dismissed for nought, the second wicket to fall after sending a thick edge off Deandra Dottin to Hayley Matthews with only 54 on the scoreboard. From a run-rate of just over three an over, Windies started to find runs hard to come by as England struck through a combined effort.
Despite early aggression from Matthews, who lifted Marsh over long on in her first over, the West Indies soon ground to a standstill against the spinners.
Three overs later, captain Stafanie Taylor chose not to review a questionable lbw decision and perished without scoring.
The World T20 champions' luck got no better as opener Matthews was trapped plumb in front by the continuously impressive Alex Hartley for a hard-earned 29.