Observed spectrum of MWC 656 (grey) compared to synthetic Be star spectra computed for different X-ray luminosities, from no X-rays up to 10³² erg s⁻¹. Our fiducial model assumes L_X = 10³⁰ erg s⁻¹, consistent with observations (Ribó et al. 2017). The HST spectrum has been re-binned to 3 pixels for clarity. Only the 10³² erg s⁻¹ model produces N V emission comparable to the data, but it simultaneously generates Si IV and C IV features that are not observed.