A Manhattan jury has convicted a daffy but dangerous drifter of possessing a scary cache of guns, daggers and bullets — weapons he somehow managed to fly coast to coast with two years ago.

James Edward O’Donnell, a dishonorably discharged Army private, was caught in March 2010 wandering the Village with eight daggers strapped to his waist, a ninth dagger in his pocket, an illegal gun in his waistband and a silencer in a sock in his backpack after plainclothes burglary cops saw him jiggling a padlock on a gated construction site.

O’Donnell faces at least 20 years in prison on 14 weapons-possession charges.