Not sure were I want to go. The Valley of Peace (pretty sure he can't go there) or Zepher's Dojo (not sure he can go there either).
The Valley of Peace is the better of the two options. Unless you can fly, the Celestial Citadel (informally called Zephy's Dojo) is inaccessible (if you've been referring to the map, it is also worth noting that the Citadel moves. Its map location is arbitrary). Even if you can fly, you would struggle to find it (its altitude is stratospheric), and it currently isn't taking guests.
The Valley of Peace would have a few issues for Amartia, but not deal-breaking.
The mist is the main feature of the mountains, as it causes negative effects on those with ill intentions. The degree of negativity depends on how ill intended a being is, ranging from mere headache or slight difficulty in breathing for those with perverted intentions to downright incapable of surviving very long for those with murderous/mischievous intentions.
The trees seem to radiate an aura of power, although it seems to only cause chaotic and/or demonic forces to avoid them, and even that effect can be ignored by such forces if given enough effort.
You could visit there, but any efforts by Amartia to spread sin would cause negative effects upon himself. Plus, Amartia is diametrically opposed to the resident deity, Niciel.
P.S. Really, there aren't any places of interest which Amartia could usefully visit between his current location and Xerxes. Save for random villages, you'd probably be best just heading straight for Xerxes.