Or we assume that - altough paranoid at the time - Seven did indeed stumble upon something and Janeway had those weapons only onboard because she secretly is a S31 agent. Unreasonable? Well lets assume that star trek intelligence knew that for some reason someone snatches ships into the deltaquadrant seemingly at random which happens to be the same direction the borg originate from. Now not only has recently opened up a wormwhole to the gamma quadrant, exposing the UFP to who knows what risks, there is enough evidence that the borg are tinkering in the Delta quadrant with forms of instant transportation to and fro the delta quadrant which makes S31 a bit nervous.SolkaTruesilver wrote: Or we can speculate Janeway had her way with the sector's quartermaster and made sure her ship was fitted with the best weapon possible so she doesn't screw up on her first assignment against a sub-powered target.
So what do they do? They sent one of their agents who happens to be mad as hatter into a region with reasonable chances of beeing snatched away and equip her with enough Tri-cobalt-devices that no matter what is on the other side, she is able to make sure there is one less wormwhole, transwarpgate whatever to worry about.