The Wisconsin HTS Axisymmetric Mirror (WHAM) extends mirror electron cyclotron resonance heating (ECRH) to 110 GHz by applying up to 0.5 MW across the 3.93 T fundamental resonance using high-field-side X-mode launch. The heating produces a strongly anisotropic population of electrons with energies reaching 0.4 MeV that remain confined for seconds after a 10 ms heating pulse. The energy-dependent onset of hard-x-ray losses is consistent with classical pitch-angle diffusion into the mirror loss cone. Diamagnetic measurements show that the long-lived population carries appreciable perpendicular pressure, while its axial distribution and CQL3D/GENRAY modeling support a sloshing-electron distribution localized near the ECRH resonance. These results demonstrate the generation and classical confinement of pressure-carrying energetic electrons in a compact axisymmetric superconducting mirror, with applications in future tandem mirror reactors.