Matthew Gabriele offered an excellent suggestion in my post below: to learn more about horses being cursed, learn whether or not horses were blessed. After a quick search I discovered, first, that I need to get myself to a library if I want to answer the question, and second, I discovered the original of the holy hand grenade. You there, yes you, you with the 20-sided die, you may be doubtful, but you will now know that I am right.
Have a look here and tell me if I’m not right. Some of the relevant portions of the image, taken from page 290 of an 18th-century volume, The Rituale Basileense juxta Romanum Pauli V et Urbani VIII include this blessing:
Benedictio Sclopetorum, & Bombardarum, fiat ex supradicta benedictione armorum mutatis mutandis, & aspergantur aqua benedicta. Benedictio Pulveris tormentarii, seu jaculatorii; item Globorum plumbeorum, vel ferreorum, conjunctim vel divisim.
In my typically hit or miss Latin, this means:
Bless the rifle and cannonball, and let the above blessing of the arms [be done] with all the appropriate changes, and let them be sprinkled with holy water. Let the gunpowder [?] be blessed, and the projectiles: namely, the bullets, whether of lead or iron, whether collectively or individually.
Thank you. Isn’t there a Medieval Academy Prize for meritorious [I spelled that right I hope] service to Geekdom?