Reddit mentions of KA-BAR 5055, Short Fighting/Utility Knife, Tanto, Black

Given the job and the terrain I'm imagining this is more of a general-abuse knife (ie, "sharpened pry-bar") than a dedicated cutter. Accordingly, I'd try not to spend a fortune on it.

Though they're not serrated I'd be inclined to get a couple of these (~$26 on Amazon) which are designed to be cheap abusable knives for this situation. If there's lots of prying to be done an interesting option would be to get a Breacher Bar, plus a sheath for it (such as this one but currently out of stock), wrap the handle with paracord and pair it with a decent folding knife (such as the RAT 1) for actual cutting.

Other usual suspects:

http://www.amazon.com/KA-BAR-Fighting-Utility-Serrated-Sheath/dp/B000BSZDP8

http://www.amazon.com/Ka-Bar-Short-Tanto-Point-Serrated/dp/B001EIALK6

http://www.amazon.com/Ka-Bar-Short-Fixed-Blade-Knife/dp/B000JMEWBC/ref=sr_1_5?s=sporting-goods&ie=UTF8&qid=1334972468&sr=1-5

(NB: with the Ka-bars make sure you get 1095 carbon steel not 440A stainless.)

http://www.amazon.com/Cold-Steel-Kraton-Handle-Concealex/dp/B000BSY9AS

Or, for something rather smaller maybe an ESEE 3.

Edit: Just remembered the Glock 78 - again it's on the sharpened-pry-bar side of things and sheath and retention are probably better than most of the options above. (It's a proper Glock product and not just some random company that's licensed the name (I'm looking at you, Smith and Wesson) and IIRC is issued in the Austrian forces.) Available in black, olive green, and sand colours. There's also a saw-back version (the Glock 81 IIRC) but I'd recommend against that.

See if he likes any of the Ka-Bar knives. They are a little more pricey in Canada, but still worth the money. Here's one that's a little bigger than the Gerber and only $12 more. For $12, you are getting an infinitely better knife.