[@Wraithblade6] Looks alright to me. I might bring up some issues with spelling, but otherwise, it's fairly good.
Three things I will say, however: first of all, the Dark Angels, and by extension the Fallen scattered through space and time, had black armour until after the Great Betrayal, so whilst the red parts of his armour are probably accurate, because Techmarine, the dark green sections ought to be black.
Second, it may be a good idea to actually describe the armour he's wearing, since it's such a major part of his appearance; [url=http://warhammer40k.wikia.com/wiki/Power_Armour#History_and_Development]this may help if you need pointers.[/url] To wit, the latest Power Armour Pattern available to the Fallen Angels at the time of the Betrayal would likely have been Mark VI Corvus, though the Mark V Heresy Pattern would be more likely for any given Fallen to wear as the earlier and more common design.
And thirdly, just as a minor query, but in his history, you say "Deciding he would rather die than waste what remained of his life on some Emperor-forsaken hellworld," as if Xepherial's lifespan is limited by aging. I just wanted to make sure you were aware that Space Marines don't seem to age, or at least nowhere near as quickly as normal humans, as they can easily live to substantially more than 1000 years old if they keep surviving their battles, as many anecdotes prove.