I do think that there has to be some common cultural understanding of what it means to have your ear cut off.
It's not often that you'll have your ear cut off by accident. It may occasionally happen in battle, of course. In the passage quoted, people didn't believe readily that the tribune had been the target. Perhaps they had a hard time believing that the perpetrator would consider it just to strike the tribune in a way that removed his ear.
Some other passages.
“Antigonus himself also bit off Hyrcanus’s ears with his own teeth, as he fell down upon his knees to him, that so he might never be able upon any mutation of affairs to take the high priesthood again, for the high priests that officiated were to be complete, and without blemish.” (Josephus, War, 1.13.9)
Leviticus 21:18 - "For whatsoever man he be that hath a blemish, he shall not approach: a blind man, or a lame, or he that hath a flat nose, or any thing superfluous..."
Apparently a Persian self-mutilated as a way to make himself appear out of favor with his king, to their enemies.
http://www.perseus.tufts.edu/hopper/tex ... ,001:3:155
The king reacted very violently to seeing a man so well-respected mutilated, and springing from the throne he uttered a cry and asked Zopyrus who it was who had mutilated him and why. [2] “There is no man,” he said, “except you, who has enough power to do this to me, and no one but I myself did this, O King, because I felt it terribly that Assyrians were laughing at Persians.” [3] Darius answered, “Unfeeling man, you give a pretty name to an ugly act if you say that it was on account of those besieged that you did for yourself past cure. Why, you poor fool, will the enemy surrender sooner because you mutilated yourself? How could you not have been out of your mind to disfigure yourself?” [4] “Had I told you,” said Zopyrus, “what I intended to do, you would not have let me; but now I have done it on my own. Now, then, if you do your part we shall take Babylon. I shall desert to the city as I am, and I shall say to them that I suffered this at your hands; and I think that I shall persuade them, and thus gain a command. [5] Now, on the tenth day after I enter the city, take a thousand men from the part of your army about which you will least care if it is lost, and post them before the gate called the gate of Semiramis; on the seventh day after that, post two thousand more before the gate called the gate of the Ninevites; and when twenty days are past after that seventh, lead out four thousand more and post them before the Chaldean gate, as they call it; allow neither these, nor the others that go before them, to carry any weapons except daggers; leave them these. [6] But immediately after the twentieth day command the rest of your army to assault the whole circuit of the walls, and post the Persians before the gate of Belus and the gate called Cissian. For I think that once I have done conspicuous things the Babylonians will give me, among other things, the keys of their gates; then it will depend on me and on the Persians to do what is necessary.”
In ancient Egypt, removing the nose and ears was a punishment for giving false testimony or for corruption.
https://www.repository.cam.ac.uk/bitstr ... sequence=1
"As Amun endures and as the Ruler endures, if I speak falsehood [replaceable by potentially any reprehensible action], may there be cut off my nose and ears, me being (banished) to Kush."
There is also a specific part of the code of Hammurabi that addresses slaves and cutting of their ear:
http://www.wright.edu/~christopher.olds ... e/Hamm.htm
If a slave has said to his master, "You are not my master," he shall be brought to account as his slave, and his master shall cut off his ear.
By contrast: "The Greeks were honourably distinguished in the ancient world for their aversion to torture and mutilation in every shape" -
http://www.perseus.tufts.edu/hopper/tex ... ry=crux-cn
To strike for the ear of the high priest's slave would be to set yourself up as the one executing a punishment for a crime where the purpose of the punishment is to humiliate and remove from respectable society (and from temple service).
"... almost every critical biblical position was earlier advanced by skeptics." - Raymond Brown