Most Leatherman multi-tools have a blade that is nestled among a bunch of screwdrivers and other tools. That means they aren't very easy to open, especially if you are wearing gloves. The OHT is an exception: it was designed so the blade would be extremely easy to open one-handed.
The blades and a few of the tools have a wide slot near the base, so you can grip it to open it relatively easily.