Don't Judge a Book by It's Cover
I never underestimate old people. Sure they may be frail looking and smell like they just pooped in their Depends, but you don't know what sort of history they might have had. They could have been a general, a gangster or a grandmaster in some deadly esoteric martial art. You just don't know.
When I was in the academy, there was a TAC sergeant who was an old Chinese American guy who was barely 5'4". Yet he had a certain bearing that suggested a military background. He spoke clearly and concisely, and his posture was perfectly vertical. He didn't slouch at all, and when he spoke his voice commanded our attention and respect without ever being raised.
The recruits and I learned later that he had been in the Navy SEALS. He was a SEAL when we were in diapers. This was not something that he revealed to us on his own accord, but we found this out through the grapevine. We tried to get him to tell us some war stories, but he was quite modest and said, "Perhaps another time."
He did relate, however, that you could never tell who would be able to make it through the training and join the SEAL teams. It didn't matter if the guy was 6 foot 200 pounds of rock solid muscle. There were a lot of 6 foot guys crying in the middle of training.
He stated that the guys that did make it through training were unassuming guys that didn't understand the concept of quitting. They were able to eat bitterness and persevere.
The last time I saw my TAC sergeant was on the news a couple of years. He was a lieutenant for an SFPD unit. The thing I admired about this guy was that his presence commanded respect. He didn't flaunt or brag, unlike a lot of the young idiots I run into nowadays. I'm always wary of shit talkers who talk crap about other people, because shit talkers are always trying to protect their egos and distract you (and themselves) from their own inadequacies.
But this guy was a leader, and we all had much respect for him. So don't underestimate the old guy. You never know where he might have derived his wisdom and experience.