yes they have the mandate... but doesn't mean they have the mandate to carry arms. just like the president, senators, congressman, Governors and Mayor can carry high powered guns as easy as that.
As i've said what can a single person do to fight insurgency when sometimes a police detachment can be run down by NPAs how much more a single person... if the NPA will attack, that weapon of the brgy captain will just add up to the weapons and ammunitions of the NPA.
If that Brgy Captain wants to fight insurgency... better make good of what was mandated to do, to provide services to his constituents, coz a happy constituents will do all they can to protect a good brgy captain.