What does' s 'st'd o' mean in English poetry?

Just remember one principle: there are only two possibilities for' hast' in English poetry, one is a well-known fixed usage like hast, and the other is to omit a single letter because of spelling and then replace it with an apostrophe. If you are interested in English poetry, I suggest that you often read Shakespeare's poems, which is very common.

For example:

Meditation = meditation

4.o'erarches=overarches

Eternity is eternity. Ever- is a prefix, meaning forever, such as ever-lastingforever.

The first question, self, is a fixed usage.

For example, losing self-control is nervousness and rudeness.

Hurt one's self-esteem.

I really don't know the second question, sorry.