An anti-neutrino can "rip a positive charge" from a proton, becoming an anti-electron, and leaving behind a neutron:
!v + p ---> !e + n
Therefore, an intense beam of anti-neutrinos could convert immense
amounts of protons, to neutrons, inside stars. Those neutrons would
then readily combine, with remaining protons, ultimately forming helium.
Thus, anti-neutrino beams could "stimulate" fusion inside stars, potentially exploding them.
To do so would, in practice, require nearly 2MeV per neutron produced, to account for the mass difference, between the products & reactants, i.e. RHS-LHS, of the above reaction equation. Thus, to explode a star, would require another star's worth of power, i.e. such would literally be a star-wars weapon.