The Chiefs threatened to drag the match into a decider.
After middle blocker JV Estrada brought the Blazers to match point with a quick attack, Arellano strung together four straight points to stay alive.
But Rocky Motol redeemed himself after committing back-to-back errors, sealing the win with a perfectly placed shot over the triple block to close the match in one hour and 53 minutes.
"Sabi ko nga, the first thing, kaya kami sumali dito is maka-gain ng experience. Especially, majority ng players ko is going into second year, kailangan nating mag-mature pa," said Blazers head coach Arnold Laniong.
"Besides ang mga kalaban mo, aminin natin na 'yung mga nakalaban natin matataas talaga. Every time na makalaban natin mga UAAP, nothing to lose sa 'tin, pero kailangang i-all out pa rin natin. Pero since ito NCAA, kumbaga ibang istorya. Kumbaga nasa isang tournament kami tayo niyan; hangga't kayang talunin, talunin," he added.
Arellano stole the opening set with captain Jiwen Sinuto and AC Guinto taking charge late, but that proved to be their last stand as Benilde clawed its way through tight situations in the third frame.
Motol led the way with 21 points built on 18 attacks and three aces, while also tallying seven digs and 15 excellent receptions. He delivered most of his production in the clutch moments of the third and fourth sets.
Kenneth Betco provided ample support with 14 points, while Mike Balbacal added nine markers, four coming off blocks.
Sinuto topscored for Arellano with 20 points, 19 off attacks, while Guinto chipped in 16 markers in a losing effort.
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