We present X-ray and multi-band optical observations of the afterglow and\nhost galaxy of GRB 180418A, discovered by Swift/BAT and Fermi/GBM. We present a\nreanalysis of the GBM and BAT data deriving durations of the prompt emission of\nT_90~2.56s and ~1.90s, respectively. Modeling the Fermi/GBM catalog of 1405\nbursts (2008-2014) in the Hardness-T_90 plane, we obtain a probability of ~60%\nthat GRB 180418A is a short-hard burst. From a combination of Swift/XRT and\nChandra observations, the X-ray afterglow is detected to ~38.5 days after the\nburst, and exhibits a single power-law decline with F_X proportional to\nt^-0.98. Late-time Gemini observations reveal a faint r ~24.95 mag host galaxy\nat an angular offset of ~0.16''. At the likely redshift range of z ~1-1.5, we\nfind that the X-ray afterglow luminosity of GRB 180418A is intermediate between\nshort and long GRBs at all epochs during which there is contemporaneous data,\nand that GRB 180418A lies closer to the E_({\\gamma},peak)-E_({\\gamma},iso)\ncorrelation for short GRBs. Modeling the multi-wavelength afterglow with the\nstandard synchrotron model, we derive the burst explosion properties and find a\njet opening angle of {\\theta}_j =>9-14 degrees. If GRB 180418A is a short GRB\nthat originated from a neutron star merger, it has one of the brightest and\nlongest-lived afterglows along with an extremely faint host galaxy. If instead\nthe event is a long GRB that originated from a massive star collapse, it has\namong the lowest luminosity afterglows, and lies in a peculiar space in terms\nof the Hardness-T_90 and E_({\\gamma},peak)-E_({\\gamma},iso) planes.