I've been using probably the same General Precision Screwdriver as you for awhile now and it works great for most small screws. There are a few that require a bit of a wrist flick to loosen. I havn't broken it yet but I was lucky to get this PLUS the General Cordless Engraver for $10 for both so not a big deal if it gives out.

For larger screws I either use a Black and Decker 7.2v Lithium Cordless Drill (very lightweight but powerful) OR a Ryobi Tek 4 Cordless Screwdriver (a bit heavier but has light on the chuck, removeable rechargeable battery, and a '2' speed setting for quick removal of loose screws).

Did you buy this? If you are trying to do case screws with that you should be using something stronger like DLSS linked.