Yes, you are right.
These are old, archaic English words. These words belong to the Early and Medieval English Literature. These words were profusely used in Shakespearean Literature. We can trace them even in the Victorian Literature, especially in poetry, as late as end of 19th century or early 20th century.
Thou = you (as a subject in the sentence)
Thyself = yourself
similar words:
Thee = you (as an object in the sentence)
Thine = yours
Thy = your
Some examples:
Thou giveth me life to live.
This life is thine.
I offer my life to thee.
Honour my life with thy blessings.
We don't use these words anymore in everyday English.
However they may still be used occasionally (very rare though!) in literature in the following situations:
* while referring to the All Mighty (God)
* while referring to a super superior and immensely powerful entity (Kings, Emperors etc.)
In fact, we use these words quite often to address God in prayers and chants, even to this day.
For example:
"Oh! Lord, thou giveth me strength to survive."
"Oh! Lord, You give me strength to survive" (modern English)
Take special care of the strange form of the verb ('giveth') in this example. That is the usual style or rule, whatever you call it.
Whenever "Thou" is used, the verb that follows turns into either "verb+th/eth" or "verb+st/est" in its past and present forms.
Hope this information helps!!