  1RXS J180408.9-342058 is a transient neutron star low-mass X-ray binary that
exhibited a bright accretion outburst in 2015. We present Nustar, Swift, and
Chandra observations obtained around the peak of this outburst. The source was
in a soft X-ray spectral state and displayed an X-ray luminosity of Lx~(2-3)E37
(D/5.8 kpc)^2 erg cm-2 (0.5-10 keV). The Nustar data reveal a broad Fe-K
emission line that we model as relativistically broadened reflection to
constrain the accretion geometry. We found that the accretion disk is viewed at
an inclination of i~27-35 degrees and extended close to the neutron star, down
to Rin~5-7.5 gravitational radii (~11-17 km). This inner disk radius suggests
that the neutron star magnetic field strength is B<2E8 G. We find a narrow
absorption line in the Chandra/HEG data at an energy of ~7.64 keV with a
significance of ~4.8 sigma. This feature could correspond to blue-shifted Fe
xxvi and arise from an accretion disk wind, which would imply an outflow
velocity of v~0.086c (~25800 km s-1). However, this would be extreme for an
X-ray binary and it is unclear if a disk wind should be visible at the low
inclination angle that we infer from our reflection analysis. Finally, we
discuss how the X-ray and optical properties of 1RXS J180408.9-342058 are
consistent with a relatively small (Porb<3 hr) binary orbit.
