Now that you've articulated what you want your axe to be capable of, my recommendation is clearly NOT what you want.

   As for sawing thru large blowdowns being exhausting with your current saw, a AXE big enough to do the job is going to be even MORE demanding physically.

You have to swing the weight of the axe overhead which increases the load on your heart by about 25% not to mention the increased risk of self-injury.
    A saw doesn't need to be used with downward force like a axe does. The sharpness of the saw does the majority of the work.

  If you do go the axe route, Fiskars makes bigger ones built just like that camp axe I recommended.
You can forget staying around 2 lbs too. A axe big enough to do what you want is going to have a 2 1/2 pound axe head or bigger plus the handle.

If you want to be able to cut big blowdowns, then a BIG saw is the way to go. Problem there is you WILL need to cash in your 401k to buy one. 

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  They make a 500mm AND a 1000mm when you want to clear the WHOLE forest.

  Here's a link to a YouTube site that features a Alaskan couple who are into Bushcraft. They both know their stuff and do alot of DIY projects. Check out his folding saw review.

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