My guardian angel would probably be any one of these five.
http://www.cracked.com/article_17019_5-real-life-soldiers-who-make-rambo-look-like-pussy.html
Seriously, Audie Murphy was basically a Mini-Master Chief. He wasn't a whole lot over five feet tall, weighed only 110lbs and was laughed at for trying to join the Marines because he was so tiny.
But despite being a borderline midget who was infected with malaria for most of the war, and who was so unpromising in training that they tried to make him a cook, he's confirmed to have killed over 240 Nazis. Read about him in the link to Cracked.com. Not bad for a guy who has a name that's a little too close to "Audrey" for comfort.
Between him and Simo Hayha (also featured in that link), I'd be nigh-on invincible. Simo Hayha (aka The White Death) fought with the Finnish Resistance against the Soviet invasion, killing a confirmed SEVEN HUNDRED AND FIFTY soldiers.
With an old hunting rifle, on iron sights. At forty degrees Celsius below zero. Really.
Did I mention he was shot in the face with a hollowpoint sniper's round, but stayed conscious long enough to return fire, kill his enemy and then pass into a coma? Well he did. And he woke up on the day the war ended.
So yeah, those would be the two best guardian angels EVER.