grammaticality - Early Modern English

In a fan-translated story I read a while ago, the protagonist uncharacteristically said some sentences using what I understand to be "Early Modern English."

He said, "I am Hathaway, the one pledged to protect only thee, e'en it mean the betrayal of all others and their eternal enmity."

I didn't see anything wrong with it when I read it at the time, but looking at it now, the sentence isn't correct in the second half. Since "e'en" is the same as "even," the sentence could be re-written as:

"I am Hathaway, the one pledged to protect only you, even it mean the betrayal of all others and their eternal enmity."

It would make more sense to add an "if" after the "even" and change "mean" to "means" (which is referring to the pledge). However, those changes don't sound very nice in the EME version if I were to add them in there.

So my question is whether maybe the original sentence was somehow grammatically correct if it was written in EME? Or, keeping as much of the original structure as possible, how could I add the changes to make the original EME sentence correct?

By the way, sorry if my question somehow isn't appropriate or is in the wrong section! (Or if my tag's wrong.) Please move it if necessary.

Answer

I think it can be made grammatically correct just by adding an "if". I'm basing this off the fact that I've found some examples of "if he/she/it mean" in some EME texts:

... if he mean as he speaketh.
_{The Historie of Great Britain Under the Conquests of the Romans, Saxons, Danes and Normans, 1623}

And if it mean the united Kingdom of Great Britain, many think it must infer an owning and acknowledgement of the Treaty of Union...
_{The Oath of Abjuration Displayed, 1712}

If it mean a just action, surely a just action is no indulgence. If it mean an unjust action...
_{A Narrative of Facts, Relating to a Prosecution for High Treason, 1795}

I'm pretty sure this is just the subjunctive, which is still sometimes used today (despite how weird it may sound).

Judging from other examples I found, it would also be OK to say "if it means", but this would lose some of the archaic flavor ;)