If you need a hefty knife with a very strong lock, this could be the Spyderco Chinook. Designed by James E Keating, it has an S30V or CPM440V bowie style blade and steel linered handles with G-10 scales. Its front lock is MBC rated, that means it sustains about 200 lbs / inch of blade.
If you want a smaller, low profile knife, that could be the Spyderco Lil Temperance. It comes in two blade shapes (bowie and spear), also CPM440V or S30V steel, full flat ground, green G-10 handles, allows tip up / down carry and it features a compression lock, also MBC rated. It's maybe the strongest folder I've ever seen.
If you want a lighter, versatile knife than the Spyderco Military will do. Also CPM440V or S30V steel, G-10 scales with a nested heavy duty (stands 100 lbs/blade inch) linerlock.
But if you want a strong, versatile, reliable and really lightweight knife, and also cheap, than get yourself a Spyderco Endura in VG-10.