When I attended the Air Force's Arctic Survival Training at Eielson AFB in central Alaska, there were two Army troops attending as well. They both brought their issue Army machetes. The AF instructors in the course told them that there was no way they were going to take those things into the field for the field exercises. Nor did they permit axes or hatchets.
The reason was simple: We were "camping" out at -35, and at those temps, a machete or an axe will just bounce off most wood. The instructors in this course had actually seen more than a few instances of this happening, even at warmer temps, hence the policy.
And, in fact, we got along just fine with knives, building both shelters and fires.
At warmer temps, these tools are safer, but I'd take a hand axe ANY day over a machete. Lots of potential for doing yourself damage with either, but especially with a machete, used improperly.
And, in a survival situation, the last thing you need is a major bleed.....
MTV