Thou is nominative. Thee is objective. English has only three cases really - nominative, objective, and possessive. I know you would hardly notice it today except for our vestigial full set of pronouns, but it's not that hard. I'm well aware it's now impossible to get people to treat thou and thee as the informal second person pronouns these days, but a writer can at least get the declension right when misusing them.
Thy and thine are both genitive, which I doubt will make mean much to most modern English speakers, and, sadly, writers. Thy was theoretically attributive ("Are those thy goods?"), and thine predicative ("The crime is thine!"). Since people also switched them around in the period, just try for: the former is used when the noun being modified starts with a consonant, the latter for a vowel - my and mine can work in the same fashion.
-st and -est are verb endings for second person singular subjects - e.g., they really only get used if the subject is thou.
e.g. - "Mine eyes have seen the wrongs thou hast wrought, and witnessed thy wickedness - have at thee!"
If a writer can't handle this, please don't let them write for Thor in your comics and movies, nor for any character that uses early-modern-style English. Please. It's glaring, the rules are simple, and it just hurts.
Furthermore, as a side note - when putting armor on female characters, please remind your artists that breasts aren't antigravity globes that happen to intersect the rib cage. They're not going to fit armor designed like they were. It just looks painful and ludicrous, and that's to a male viewer. Please stop that.
Thank you,
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smarriveurr