Bow saw ideal for cutting up branches and logs. The blade is designed for green wood (live branches) but will work on dry wood too, just not as efficiently.
Normally sell for about £16 (look for the Amazon price on the right side of the screen). It's not in stock at the moment, but Amazon have been selling these forever so I'd expect they will get stock soon.
Dry wood bladed version is also out of stock but available to order for same price here https://www.amazon.co.uk/dp/B0001GS14A?psc=1