  Particle acceleration and pitch-angle anisotropy resulting from magnetic
reconnection are investigated in highly magnetized ion-electron plasmas. By
means of fully kinetic particle-in-cell simulations, we demonstrate that
magnetic reconnection generates anisotropic particle distributions $f_s \left(
{|\cos \alpha|,\varepsilon} \right)$, characterized by broken power laws in the
particle energy spectrum $f_s (\varepsilon) \propto \varepsilon^{-p}$ and pitch
angle $\langle \sin^2 \alpha \rangle \propto \varepsilon^m$. Their
characteristics are determined by the ratio of the guide field to the
reconnecting field ($B_g/B_0$) and the plasma magnetization ($\sigma_0$). Below
the break energy $\varepsilon_0$, ion and electron energy spectra are extremely
hard ($p_<\lesssim 1$) for any $B_g/B_0$ and $\sigma_0 \gtrsim 1$, while above
$\varepsilon_0$, the spectral index steepens ($p_> \gtrsim 2$), displaying high
sensitivity to both $B_g/B_0$ and $\sigma_0$. The pitch angle displays
power-law ranges with negative slopes ($m_<$) below and positive slopes ($m_>$)
above $\varepsilon_{\min \alpha}$, steepening with increasing $B_g/B_0$ and
$\sigma_0$. The ratio $B_g/B_0$ regulates the redistribution of magnetic energy
between ions ($\Delta E_i$) and electrons ($\Delta E_e$), with $\Delta E_i \gg
\Delta E_e$ for $B_g/B_0 \ll 1$, $\Delta E_i \sim \Delta E_e$ for $B_g/B_0 \sim
1$, and $\Delta E_i \ll \Delta E_e$ for $B_g/B_0 \gg 1$, with $\Delta
E_i/\Delta E_e$ approaching unity when $\sigma_0 \gg 1$. The anisotropic
distribution of accelerated particles results in an optically thin synchrotron
power spectrum $F_\nu(\nu) \propto\nu^{(2-2p+m)/(4+m)}$ and a linear
polarization degree $\Pi_{\rm lin} = (p+1)/(p+7/3+m/3)$. Pitch-angle anisotropy
also induces temperature anisotropy and eases synchrotron cooling, along with
producing beamed radiation, potentially responsible for frequency-dependent
variability.
