Slipjoint knives are fine if used properly and are suitable for 99% of the tasks you might find while hiking-- food prep, fire-making fuzz sticks, repairs to equipment, etc. Most of the accidents with slipjoints come from using the point and that needs real caution.
Swiss Army knives can deliver a lot of utility in a small package. IMHO, the medium 93mm knives with a saw and awl make the best trail tools for the weight. My favorites are the Hiker, Fieldmaster, and Farmer models.
The larger Victorinox 111mm models have locking blades. The one-handed Trekker model is an excellent trail knife. BTW, Wenger makes several medium sized Swiss Army knives with locking blades and are not given their due. Check out the EvoGrip S 17 model for an excellent trail tool.
There are many good pocket knives made with securely locking blades and are my preference for an all-round knife. The Benchmade Griptilian is available in two sizes and is a strong design with excellent steel (154cm). The Gerber LST models are light and inexpensive. Spyderco makes a number of lightweight knives with good locks and steel.
If you elect to carry a single blade knife, adding a Victorinox Classic gives scissors, tweezers and toothpick. A locking folder plus a Leatherman Micra makes an excellent combination.
For fixed-blade knives, the Swedish Mora knives are quite light and very inexpensive. The new Craftline Allround has a thicker 2.5mm stainless blade and weighs 4 ounces with the sheath--- for $12.50! It is really all the knife you need and suitable for survival skills like making fire drills, figure-4 traps, and fuzz sticks. It is an excellent food prep knife as well. The blade design is identical to "bushcraft" knives costing ten times as much. Add a Classic or Micra to this knife and you can go anywhere.