I was wondering if anyone has any insights here about the definition of "Security" when used to describe the TSA?

(please keep in mind i do not use drugs)
If a person was to bring a bag of weed onto a domestic flight, (international being another discussion entirely) would the TSA be allowed to confiscate it?

If their mandate is to provide for security on a plane, this would have nothing to do with the bag of weed.

Other than acting as peace officers (is this in their mandate?) what right do they have to seize drugs?

Wouldn't weed actually make it safer, with everyone being a little more mellow?