I think the point of drawing attention to the fact that Paul is writing this with his own hand is to emphasise his personal relationship with the Galatians and how important it is to him that they hear his message. He’s not just some far off academic scholar pontificating on an obscure theological point that doesn’t really matter too much if they take it or leave it. Paul really cares about the Galatians, and the message of this letter is really important. He also writes in large letters to emphasise how important this message is. From what Paul has heard about the Galatians, it sounds like they’re turning away from Christ, which would be disastrous, so to make sure they take this letter seriously, he wants them to know that he’s not just dictating it to a scribe, he’s signing it himself. So we should have that in mind as we go on to look at Paul’s conclusion to this letter. It is absolutely vital that we understand and take on board what Paul is saying.