Samoa started the match brightly, refusing to concede an inch and coming forward across the court to apply defensive pressure, while on attack they showed glimpses of brilliance, with former Silver Ferns hopeful Julianna Na'oupu impressing in her test debut.
Despite closing the margin to within one, basic errors, including 11 first-quarter turnovers, hurt Samoa's cause, before the Silver Ferns managed five straight goals to help them to a 19-9 lead at the first break.
There were positive signs at the Silver Ferns' attacking end, with Halpenny and Tutaia varying options and sharing the scoring and distribution work. Both players benefited from Rasmussen's flair and athleticism on the flank and Camilla Lees' speed in the midcourt as the Kiwis began capitalising on swift transitions between defence and attack.
A lighting malfunction interrupted play early in the second term and offered Samoa a chance to regroup, but on the resumption New Zealand maintained their speed and efficiency in attack to finish the half ahead 39-15.
Mass changes at the break saw Bailey Mes, Jodi Brown and Shannon Francois injected into the attack, and despite taking time to find their feet the Ferns kept up their intensity and began to dominate.
Young goal keeper Phoenix Karaka was retained on court for the second half, in just her second test outing after missing the Fiji game with a tendon injury, and combined well with the fresh-legged Grant to maintain their speed and power out of the defensive end.
Errors and fatigue combined to bring the referee's whistle into the scrappy dying stages, but with Samoa suffering a crisis of confidence the Silver Ferns powered home for an emphatic victory.