The night was clear,
All they (They all?) stood together,
When the black foal was born,
known as a stalwart stallion later.
The (His?) herd run (ran) free in Eotheod,
No stable shall (did) they need.
Their breed of grace and lineage,
A strain (race?) of mighty (many?) years. (strain sounds a little like they were annoying)
Still young the horse know (knew) his rider,
Never having fellt the whip.
Like a home the court near Snowbourne lies,
And ever free in mearce (? not sure of this word) he graze(s).
The white horse lead the Eohre (Eored?),
and bore his master with no (without?) fear.
But terror brought the Ulaire,
not only with (With more than) horrorful (horrible?) black darts to him.
A victory with tears is ward (not sure what you mean here, ward as in 'guarded'?),
and still a stone on this place speaks:
"Faithful servant yet masters bane,
Lightfoot's foal, swift Snowmane"
Hope this helps, but it is so hard to criticise poetry because by its very nature, there are no 'rules' as such. Keep at it Neesa!