Paul's own hand

Galatians 6:11 - See what large letters I use as I write to you with my own hand!

I wonder why Paul decided to write part of this letter with his own hand. Did he want to prove he was actually present dictating the rest of it to his scribe? Would there be any doubt about that in the Galatians' minds?

Had his scribe stepped out of the room for a break leaving Paul with nothing better to do? Did Paul write more than this one sentence in his own hand? Did he finish the letter himself?

Why did he use large letters? (Some think he may have had poor eyesight.) Was it just to distinguish his writing from that of his scribe? What made him think to write those particular words; that is, that particular self-referential sentence? Was he trying to be humorous?

Did later scribes copy Paul's handwriting in large letters to help preserve the difference and meaning? Do any handwritten copies in existence today (We don't have the originals.) have larger print for this verse?

Did Paul have neat penmanship?