Definition of "sacrificer"

Our course will seem too bloody, Caius Cassius,To cut the head off and then hack the limbs,Like wrath in death and envy afterwards;For Antony is but a limb of Caesar:Let us be sacrificers, but not butchers, Caius.

1599 (first performance), William Shakespeare, “The Tragedie of Iulius Cæsar”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act II, scene i]

In this you’have made the Court the Antipodes,And will’d your Delegate, the vulgar Sunne,To doe profane autumnall offices,Whilst here to you, wee sacrificers runne;

1631, John Donne, “To the Countesse of Bedford”, in Poems‎, London: John Marriot, published 1633, p

So, when some brawny Sacrificer knocks,Before an Altar led, an offer’d Ox,His Eye-balls rooted out, are thrown to Ground;

1717, John Dryden [et al.], “Book 12”, in Ovid’s Metamorphoses in Fifteen Books. […], London: […] Jacob Tonson, […], page 418

[…] no sacrifice is valid unless the sacrificer lay his hand upon the head of the victim.

1908, Helen Keller, chapter 3, in The World I Live In‎, New York: Century, page 35