Plead vs Obtest - What's the difference?

As verbs the difference between plead and obtest

is that plead is to present an argument, especially in a legal case while obtest is (archaic|ambitransitive) to implore, beseech, plead, beg.

To present an argument, especially in a legal case.

* Bible, Job xvi. 21

O that one might plead for a man with God, as a man pleadeth for his neighbour!

To beg, beseech, or implore.

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(en verb)

(archaic, ambitransitive) To implore, beseech, plead, beg.

(archaic, ambitransitive) To call on a witness (often God) to confirm that something is true.

(Dryden)