Americans - with their well-known love of the "Smaller is better" concept (

) - will recommend that you take a 30" kukri, backed up by a 24" kukri, backed up by a Busse Battle Mistress, backed up by a BK7, backed up by a CS Trailmaster, backed up by a Swamp Rat... You get the picture. An armchair commando can carry anything!
Take a Victorinox Swiss Army Knife with a mix of tools appropriate to your needs.
Take a multitool of the Gerber/Leatherman type.
If you have a definite, identified need for one, take a 2" to 4" locking folder made by a good manufacturer. Names include (in alphabetical order) Benchmade and Spyderco
Take a small torch, preferably LED running on AA cells. (
Seriously consider a Petzl head torch).
As to anything else, you don't provide many hints.
Best of luck,
maximus otter