The force of the particle ὡσεὶ falls on θρόμβοι, not on αἵματος, as is evident from the fact of it (not αἵματος) having the epithet, and in the Plural, καταβαίνοντες. The blood streaming from the pores in smaller drops became clotted together by reason of its copiousness. If the sweat had not been a bloody one, the mention of blood might have been altogether omitted, for the word θρόμβοι even by itself was sufficient to express thick sweat.—ἐπὶ τὴν γῆν, upon the earth) by reason of its copiousness. Thereby the earth received its blessing.
The form of the expression, “as it were, great drops (better, clots) of blood,” leaves us uncertain, as the same Greek word does in “descending like a dove,” in Matthew 3:16, whether it applies to manner or to visible appearance. On the latter, and generally received view, the phenomenon is not unparalleled, both in ancient and modern times.
...but the case rather seems to be this, that the pores of Christ’s body were so opened, that along with sweat came out blood, which flowed from him very largely; and as it fell on the ground, he being fallen on his face to the earth, it was so congealed by the cold in the night season, that it became really, as the word signifies, clots of blood upon the earth.