You missed the point if you thought it was just the words of a dying wife telling how to beat aliens. Since that point of his wifes death, Gibson's character loses his faith who heretofore had been a priest. Being fucking depressed and hating God, assumes everything has no meaning, no interrelation, everything is a long line of coincidences.
Flash forward to the end and his stupid daughter leaving cups of water all over the house which he thought was just an annoying bad habit. To his brother being a shitty baseball player leaving an old bat in the house. His gimp son who had asthma, and his dying wife who said "swing away" which he thought was a random memory of his brothers baseball play.

The asthma blocks the aliens hand gas preventing it from killing the kid, the baseball player cracks the alien in the head knocking him into a glass of water which scalds him, he "swings away" at the other glasses of water nearby further injuring the alien. And after it's all over he realizes every seemingly shitty event that's happened in the last 10 years has been leading up to this point. Ergo, faith restored.

I still really enjoy this movie as only this and Sixth Sense (maybe even Unbreakable) are Shaymalanians redeeming movies.