Based on this, if you're at a friend's house, it is perfectly legal for him to get his handgun out to show you. But you can't pick it up yourself (even if he tries to hand it to you), because then you would be in possession of an unconcealed handgun off your own property.
Now suppose you don't have a CHL and you take your Glock in its case over to your friend's house. As we saw, the law doesn't even allow you to carry your cased handgun into your friend's house. But, with your permission, your friend could come out to your car (assuming it's parked in his driveway), pick up the gun, and carry it into his house. While you're there, it's perfectly legal for your friend to handle your gun (since it's on his property), but it's illegal for you to handle it (since it's not currently on your property).
Finally, suppose you actually do have a CHL and you legally carry your Glock into your friend's house, holstered and concealed beneath your untucked shirt. Your friend knows you carry and would like to see it, but you want to make sure you do everything legally. You can't just remove the gun from its holster and hand it to him. But if you give your friend permission to reach under your shirt and remove the gun from concealment, that should be legal, as long as your friend is the one holding the gun at the instant it's exposed. Or you could go to another room by yourself, hide the gun in a shoebox or wrap it in a towel, etc., and then go back into the room where your friend is and allow him to take the gun out from its container.
Needless to say, this is ridiculous. There's no way the legislature intended this; it has to be an oversight. PC §46.02 needs to be amended by inserting something like the following:
True enough, it's extremely unlikely one would EVER be arrested, much less charged and tried, for something like this. But that doesn't change the legality vs. illegality of it.(3) carr'ying at a private residence or place of business, with the consent of the owner or someone with authority to act for the owner.