Objection 1. It would seem that the angels did not receive grace and glory according to the degree of their natural gifts. For grace is bestowed of God's absolute will. Therefore the degree of grace depends on God's will, and not on the degree of their natural gifts.
Objection 2. Further, a moral act seems to be more closely allied with grace than nature is; because a moral act is preparatory to grace. But grace does not come "of works," as is said in Romans 11:6. Therefore much less does the degree of grace depend upon the degree of their natural gifts.
Objection 3. Further, man and angel are alike ordained for beatitude or grace. But man does not receive more grace according to the degree of his natural gifts. Therefore neither does the angel.
On the contrary, Is the saying of the Master of the Sentences (Sent. ii, D, 3) that "those angels who were created with more subtle natures and of keener intelligence in wisdom, were likewise endowed with greater gifts of grace."
I answer that, It is reasonable to suppose that gifts of graces and perfection of beatitude were bestowed on the angels according to the degree of their natural gifts. The reason for this can be drawn from two sources.
First of all, on the part of God, Who, in the order of His wisdom, established various degrees in the angelic nature. Now as the angelic nature was made by God for attaining grace and beatitude, so likewise the grades of the angelic nature seem to be ordained for the various degrees of grace and glory; just as when, for example, the builder chisels the stones for building a house, from the fact that he prepares some more artistically and more fittingly than others, it is clear that he is setting them apart for the more ornate part of the house. So it seems that God destined those angels for greater gifts of grace and fuller beatitude, whom He made of a higher nature.
Secondly, the same is evident on the part of the angel. The angel is not a compound of different natures, so that the inclination of the one thwarts or retards the tendency of the other; as happens in man, in whom the movement of his intellective part is either retarded or thwarted by the inclination of his sensitive part. But when there is nothing to retard or thwart it, nature is moved with its whole energy. So it is reasonable to suppose that the angels who had a higher nature, were turned to God more mightily and efficaciously. The same thing happens in men, since greater grace and glory are bestowed according to the greater earnestness of their turning to God. Hence it appears that the angels who had the greater natural powers, had the more grace and glory.
Reply to Objection 1. As grace comes of God's will alone, so likewise does the nature of the angel: and as God's will ordained nature for grace, so did it ordain the various degrees of nature to the various degrees of grace.
Reply to Objection 2. The acts of the rational creature are from the creature itself; whereas nature is immediately from God. Accordingly it seems rather that grace is bestowed according to degree of nature than according to works.
Reply to Objection 3. Diversity of natural gifts is in one way in the angels, who are themselves different specifically; and in quite another way in men, who differ only numerically. For specific difference is on account of the end; while numerical difference is because of the matter. Furthermore, there is something in man which can thwart or impede the movement of his intellective nature; but not in the angels. Consequently the argument is not the same for both.
Source: Summa Theologica (New Advent)