Like many features of Skyhold, these four statues are not original to the structure. Scratchings much newer than the sculpture suggest these were placed by Fereldans as representations of Andraste. Typical appropriation; these are not Our Lady. They are altered Chasind figures, and likely had animal heads or some such. The number suggests the barbarian tradition of personifying seasons as female warriors, bearing the typical attributes of renewal and death. Winter is of note for its brutality, as it is tied to their rumored custom of killing those who flee battle. Harsh enough, but more so when you note that killing the fleeing was not left to fellow soldiers, but common citizens waiting to meet them at their camps. Such was their commitment that death at the hands of their people was welcomed over the shame of broken morale. Such is the brutality of their animist gods.
Here follows a relevant page from historic examination:
For She of All and War will dade,
And issue forth as with a spur,
And welcome home she will the bold,
Returning them with crowns and brand.
But knowing runs the empty hand,
That all that waits is falling cold.
For such the shame to flee a cur,
Is glory saved with mother's blade.
—From Barbarian Blood: Chasind Myth Made Sensible, collections of the University of Orlais