Weber did mean to legitimize the state but his reasoning can easily be turned from prescriptive to descriptive: we define the state as merely the entity with monopoly on violence over an area. Who decides what is “legitimate” violence? Why, the state, of course: by definition, it has the means to impose its views.

The Weberian idea is there are legitimate non-violent politics that the state offers itself to, which therefore allow the state to use violence against unlegitimate politics that don’t “play by the rules”. However since the state itself decides what is legitimate or not, and since any illegitimate political group will turn illegal else disappear when faced with the violence of the state, we just land back where we started: the state has a monopoly on violence and that is what decides what is “legitimate” politics, and therefore what is legitimate violence. The state calls its own violence “law”, but that of others “crime”.

The current labelling of political opponents as terrorists by the US government is illustrative of that. Some Weberians have you believe that is all legitimate since after all there indeed was an election