  JWST has recently discovered a subset of reionization era galaxies with
ionized gas that is metal poor in oxygen and carbon but heavily-enriched in
nitrogen. This abundance pattern is almost never seen in lower redshift
galaxies but is commonly observed in globular cluster stars. We have recently
demonstrated that this peculiar abundance pattern appears in a compact ($\simeq
20$ pc) metal-poor galaxy undergoing a strong burst of star formation. This
galaxy was originally selected based on strong CIV emission, indicating a hard
radiation field rarely seen locally. In this paper, we present JWST/NIRSpec
observations of another reionization-era galaxy known to power strong CIV
emission, the $z=7.04$ gravitationally-lensed galaxy A1703-zd6. The emission
line spectrum reveals this is a metal poor galaxy ($12+\log(\rm O/H) =
7.47\pm0.19$) dominated by a young stellar population ($1.6^{+0.5}_{-0.4}$ Myr)
that powers a very hard ionizing spectrum (CIV EW = 19.4 $\unicode{x212B}$, He
II EW = 2.2 $\unicode{x212B}$). The ISM is highly-enriched in nitrogen
($\log(\rm N/O)=-0.6$) with very high electron densities ($8-19\times10^4$
cm$^{-3}$) and extreme ionization conditions rarely seen at lower redshift. We
also find intense CIV emission (EW$\gtrsim20$ $\unicode{x212B}$) in two new
$z\gtrsim 6$ metal poor galaxies. To put these results in context, we search
for UV line emission in a sample of 737 $z\gtrsim 4$ galaxies with NIRSpec
spectra, establishing that 40(30)% of systems with [OIII]+H$\beta$ EW
$>2000\unicode{x212B}$ have NIV] (CIV) detections with EW$>5$ $\unicode{x212B}$
($>10$ $\unicode{x212B}$). These results suggest high N/O ratios and hard
ionizing sources appear in a brief phase following a burst of star formation in
compact high density stellar complexes.
