Am I the only one who thinks the idea of held items are a little cheap? I thought in the Pokemon world, serious competitive battles are supposed to be a test of the trainer and Pokemon's strength. But then you start attaching balloons, blinding dust, power-enhancing orbs, assault vests, etc. and then you start to see many variables.

What even constitutes a held item? Why can I use a Pokemon wearing an assault vest in a competitive battle, but not, say, a knife or a gun?