I don't think knives are very heavy in general– given the utility.
My EDC (every day carry) is a Benchmade Griptilian with a bright orange handle. 3.9oz., excellent steel, easy to open one-handed, good pocket clip, great ergonomics– works for lefties with no compromises. It is stout enough for survival and easy to carry.

My favorite fixed blade (du jour) is the Mora 2010. It is inexpensive, 5.1oz, stout and sharp. About $35 on eBay.

Want a great food prep knife? Get a Victorinox paring knife. Stainless 3.25" serrated blade, 3/4oz. and about $4.50 (model 49693). Sharp as blazes and dirt cheap. Commercial fishermen use them for all kinds of net and bait work. I wouldn't recommend one for survival, but I'd be happy to have one. It can cut line, prep food and make fuzz sticks for fire starting.

Best Swiss Army knife? I like the Hiker: 2 blades, saw, awl, Phillips, flat blade screwdrivers, can opener, bottle opener. The Trekker model is a big knife with a locking blade and tools. That and a Classic will take you anywhere.
A Victorinox Classic lives on my keychain along with a firesteel, whistle, LED flashlight and spy capsule. Most used implements: scissors and toothpick.
The Spyderco Ladybug is a neat little single blade folder. 2" blade, 0.6oz/18g. Mine is bright orange.
