West and Will are a complicated pair to write. They have such different experiences with the Major. Which is why West speaks to Jacob and the boys about Grandpa Carter differently than any of the others.
I tend to assume the message was the watch, and the regret that comes when you need to say you're sorry to someone but you know you will never get the chance. Will and his father aren't in that place, Will is still very haunted by the Major, and there is a moment, later in this book where that is addressed, and it's Jacob that really addresses it. You'll see
Jacob is a warrior, Will assumes he gets it from Andrew, but Jacob is Will's son as well, and the warrior in him is just as much his.