If your palms are sweaty then you have problems that moleskin is not going to solve. While I see that you are putting it on plastic, as opposed to metal, all you are going to do is have a space where sweat and all the funk on your hands will stay moist for a while. That gives the funk time to multiply. Fuzzy funk may or may not work as camoflage but I would not want to be the one to test it out.
If you are looking for "grippiness" think either skater's tape, stair tread tape, or the old-fashioned tacky cloth elictrical tape (do they even make that stuff any more?).
Just for fun, where did you hear/read that .mil folks wrap their firearm in moleskin to absorb sweat? I'm not going to come right out and say that Seel Team 0.08 was the source, but I have my thoughts on that. Most .mil that worry about sweat are concerned with keeping a grip as opposed to absorbing the sweat.