Night and Day

[SimikPK]

You are the day.
I am the night. The first wo lines sound cliché to me - just showing a very obvious contrast.
You are the light.
I am the dark. The second two lines add nothing new to what is already said.
But in your sights all flames are dull,
and embers embrace a stiller soul.
You shine so bright it's hard to bare, The idea included here is nice - the day stronger than everything else that gives light, but do you need to say this one point in three lines? Bear spells like this, not *bare. Sould and dull do not rhyme too well.

so I offer you my cloak to wear. This is the strongest point of the poem, IMHO - the night actually helping the day + the mortals, making the day meaningful.
For my embrace on either side, Both-sided embrace is nice image.
gives mortal eyes a place to hide.
The fairest face has power more
than earthly creatures can endure. Here it is repetition of what is already said - that they cannot endure it is suggested already in the "place to hide"
And what a pity it would find
to, by your brilliance, turn them blind.
The world of light can now be shown,
because my shadow has been thrown. Again repetition of the already said things: the lyrical subject has already "offered the cloak".
You are the day.
I am the night.
And by my darkness, 
light is known. Last four lines do not say anything new, everything has already been said.

Additionally, there seem to me to be too many topic to this poem, none elaborated enoug - I and you being night and day, the day being too strong, the night´s concern for the "mortals", the night helping the day + shielding the mortals... Choosing the central topic - "the night gives meaning to the day, resp. makes day acceptable" and elaborating on it would make the point of this poem stronger.

The rhythm in the middle section flows quite well due to the rhyming, however, the first and last four lines don´t.