  We have identified a broad absorption line (BAL) outflow in the HST/STIS
spectrum of the quasar QSO B0254-3327B at velocity $v=-3200\text{ km
s$^{-1}$}$. The outflow has absorption troughs from ions such as Ne VIII, Na
IX, Si XII, and Ne V. We also report the first detection of S XIV absorption
troughs, implying very high ionization. Via measurement of the ionic column
densities, photoionization analysis, and determination of the electron number
density of the outflow, we found the kinetic luminosity of the outflow system
to be up to $\sim1\%$ of the quasar's Eddington luminosity, or $\sim5\%$ of the
bolometric luminosity, making it a potential contributor to AGN feedback. A
solution with two ionization phases was needed, as a single phase was not
sufficient to satisfy the constraints from the measured ionic column densities.
We find that the ionization parameter of the very high-ionization phase of the
outflow is within the expected range of an X-ray warm absorber. We also
examined the physical properties of the outflow of Q0254-334 along with
previously studied extreme UV outflows, with a total sample of 24 outflow
systems, finding a weak negative correlation between outflow velocity and
distance from the central source, with larger distances corresponding to slower
velocities. The very high-ionization phase of the Q0254-334 outflow has one of
the highest ionization parameters of UV absorption outflows to date, which we
attribute to the presence of S XIV.
