The Marlins (10-8) avenged a one-goal overtime loss last week to Shenandoah (12-5) with the tournament victory.
VWC now moves on to the tournament semi-finals against No. 2 Randolph-Macon. That game will be played Wednesday in Ashland, Virginia.
After the two teams traded the first four goals of the game, with Cortney Gensemer scoring twice for the Hornets, Virginia Wesleyan took control of the game by scoring five straight from the 16:58 to 5:54 marks of the first.
Shenandoah, which won seven of 21 draws on the day, won the ensuing draw but turned the ball over at midfield with 22 seconds left and the Marlins struck, scoring 12 seconds later to push their advantage back to four goals.
VWC opened the second half by scoring the first two goals of the stanza, but more importantly keeping the Hornets off the board until Arndt fed sophomore classmate Becky Bove at 13:49.
Bove's goal, her fifth of the season, started a 4-1 Hornets run to finish the game, but the rally proved to be too late.
Senior Liz Bereit had the squad's final goal of the season, an unassisted tally with 2:13 remaining.
Bereit finished the year with 51 goals, the fifth-best season in program history, and her 161 goals is third-best all-time.
Virginia Wesleyan outshot its hosts 35-26 with SU picking up 22 of the game's 42 groundballs.
Both goalkeepers played outstanding, with Rachel Levy turning away 15 shots for the Hornets and Madison Carroll 14 for the Marlins.
Shenandoah will announce its 2015 schedule in mid-summer.