We present a study of X-ray ionization of magnetohydrodynamic (MHD) accretion-disk winds in an effort to constrain the physics underlying the highly-ionized ultra-fast outflows (UFOs) inferred by X-ray absorbers often detected in various sub-classes of Seyfert active galactic nuclei (AGNs). Our primary focus is to show that magnetically-driven outflows are indeed physically plausible candidates for the observed outflows accounting for the AGN absorption properties of the present X-ray spectroscopic observations. Employing a stratified MHD wind launched across the entire AGN accretion disk, we calculate its X-ray ionization and the ensuing X-ray absorption line spectra. Assuming an appropriate ionizing AGN spectrum, we apply our MHD winds to model the absorption features in an {it XMM-Newton}/EPIC spectrum of the narrow-line Seyfert, pg. We find, through identifying the detected features with Fe K$alpha$ transitions, that the absorber has a characteristic ionization parameter of $log (xi_c [erg~cm~s$^{-1}$]) simeq 5-6$ and a column density on the order of $N_H simeq 10^{23}$ cm$^{-2}$, outflowing at a characteristic velocity of $v_c/c simeq 0.1-0.2$ (where $c$ is the speed of light). The best-fit model favors its radial location at $r_c simeq 200 R_o$ ($R_o$ is the black hole innermost stable circular orbit), with an inner wind truncation radius at $R_{rm t} simeq 30 R_o$. The overall K-shell feature in the data is suggested to be dominated by fexxv with very little contribution from fexxvi and weakly-ionized iron, which is in a good agreement with a series of earlier analysis of the UFOs in various AGNs including pg.
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