Generally you want a lightweight saw. For what you are talking about I would suggest a 40-45cc saw with a 16" bar. That should do him nicely.

Weight can be an issue but for the short durations it sounds like he uses it, I don't think you'll need to spend extra to get a lighter saw. An example of what many consider to be a too heavy saw is the Stihl MS290. It weighs in at 13lbs, and I believe that is without fuel and oil. The MS270 is slight smaller but 1.3lbs lighter at 11.7lbs. My MS260 is the same size engine as the 270, about the same power but it is 1.1lbs lighter at 10.6lbs. There are other differences between the 260 and 270 but nothing you should worry about for the amount he will use the saw.

Being a guy he may have a strong preference to a brand. If you are really unsure, you could try the gift certificate route, or get him a saw from a dealer with the understanding that you may be back to exchange or even return it if it is not the brand he wanted.

The 45-50cc range is good. You can fudge that range and go 40-60cc to give you more choices if needed.

If he is not mechanically inclined to fix 2 cycle engines, then stick to a brand that has good support in your area. That will likely be Husqvarna and Stihl.

Has he mentioned any particular brand of saw that he likes? What saw does he use now?

Something else to really consider are chaps, gloves, and a helmet with ear protection. A complete safety package will run ~$100 but that cost is nothing compared to the damage it can prevent or lessen.

Good Luck.