Jarvis kicked seven penalties in a faultless performance but it was not enough for the Wizards.
The Welsh All blacks scored tries through wing Chris Morgan and centre Gareth McCarthy, while fly-half James Thomas landed six penalties to seal a 28-21 victory.
Elsewhere, Bedwas edged out Cross Keys in a mid-table thriller at Bridge Fields.
Full back Stuart Thomas kicked off the try scoring for the home side, followed by two tries from pacy winger Elliot Foils, and one-apiece from scrum-half Gareth Williams and flanker Phillip Sargent.
The Keys did engineer four tries of their own, with prop Craig Gould crashing over twice and No8 Mark Popham and flanker Robert Nash also crossing, but it wasn’t enough as Bedwas eventually ran out 36-27 victors.
Pontypool heaped more misery on lowly Carmarthen Quins in their clash at Carmarthen Park.
Pooler center Dan Robinson scored the first try, followed over by No8 Luke Dyckoff.
Full back Tom Hancock had a fine kicking game, hitting four penalties and a conversion, as Pontypool secured a 29-19 win.
Glamorgan Wanderers continued their dreadful form with a ninth consecutive loss against Tonmawr at the Memorial Ground.
The Pitmen proved too strong for Wanderers, churning out five tries. Two came from wing Kiba Richards, while there was one each for scrum-half James Donovan and flanker Ben Davies, in addition to a late penalty try.
Dai Flanagan pulled all the strings at fly-half, scoring three penalties and converting four of the tries for Tonmawr as they coasted home 42-19.
