Best Overall
The unique design of this V-shaped head allows it to trim anywhere safely and comfortably. But it's particularly good for the chest/stomach area or even legs and arms. That's because the vertically-set blade allows you to sweep it over the skin like a brush and the “skin protective blade technology” helps reduce skin irritation, cutting body hair cleanly in whatever direction you choose. The adjustable 3-12mm trimming guard gives you full control of how much hair you want to leave on your body and this is built to get into every nook and cranny.
Wet/dry body trimmer,
$109.99 by Panasonic
FYI: To tame wild armpit hairs, simply raise your arm above your head and then bring it straight down to your side. See those hairs peeking out? Get rid of them with your trimmer. Do this twice to catch any stragglers.