Round patches are less prone to fraying or lifting than square ones. Pliers tend to add a lot of weight to a tool, though, so decide for yourself whether they're really necessary. If you do, be sure your tool has one of these, as they're tough to improvise. Awls are used to punch holes in straps or belts. Since they're often short and stout, they also make good prying tools.
Most tools have little engraved rulers on their sides, which is useful to measure tracks or insects.
They add zero weight to the tool. Good for cutting fire twigs, carving a walking stick and cutting through webbing and other tough fabrics. I like to have them on hand for post-trip festivities. Look over your gear and decide what sort of screwdrivers you'll need to cope with all possible fix-it jobs. Flat-head screwdrivers are good to have for stove repairs.