Old English bletsian, bledsian, bloedsian: to consecrate by religious rite, from Proto-Germanic blodison, hallow with blood, the original sense a blood sprinkling on pagan altars, compare Old Icelandic reddening the altar with blood. Henry Sweet's 1880 derivation won the dictionaries; Flasdieck's 1958 counter-derivation from blotan, to sacrifice, won the Germanists. Either way the word is pagan ritual stock, which is exactly Liberman's puzzle: the missionaries had Latin benedicere, speak well of, and instead hung the new religion's key verb on one of the most pagan words of the old ritual.
The apologists' answer for the missionaries' choice: blood consecration was not foreign to the Hebrew scriptures, Leviticus 17:11, the blood that maketh atonement, and Christianity's own claim, Hebrews 10, is that one sufficient blood replaced all the insufficient ones, so the old word preached the new doctrine perfectly, every pagan and Jewish sacrifice pointing to the final one. The verb that meant sprinkle the altar became the verb for the sacrifice that retired all altars. The missionaries did not tolerate the pagan word. They weaponized it.
The claim: bless is the archive's cleanest case of meaning as inherited weapon, the word carried its ritual charge from altar to church because the power was the point, and every modern blessing, sneeze-response, televangelist decree, still runs on the ancient circuit: consecration by transferred substance, blood then, words now, the mechanism unchanged, the medium deodorized. Verdict: the semantic archaeology supports it. The archive's Bless you file documents the same circuit's everyday voltage. The blood left the word. The consecration never did. Ask what gets sprinkled now.
If blessing began as blood-sprinkling, what got lost when the blood dried out of the word?