I find that with a MoD4 Survival Knife with a Fallkneven DC4 + Bacho Laplander + half a dozen Fatwood Sticks it doesn't present too much of a problem getting a fire started when processing 6-8 inch logs.

If using a wood burning stove you may need to quarter or greater the logs if more than 3-4 inch diameter especially if the logs haven't been dried out. Sawing logs generally require less energy than using an Axe. The saw will generally be lighter. The axe will both cut and split logs.

https://www.youtube.com/watch?v=X5W6r5U7yBE

A 24 inch Bacho Force Bow saw will easily deal with the larger logs and is still somewhat portable weighing 720 gms.

http://www.amazon.co.uk/Bahco-BAH102423-10-24-23-Bowsaw-24In/dp/B0001IX7TC/ref=pd_sim_diy_6