An update to the Wacom One situation

A while ago I received a Wacom One pen tablet and it only came with the tablet for itself. I contacted Wacom support and they gave me the pen for free and the cable on a discount. It arrived today and is working fine! I do have a question though, why does it feel so clunky? Do I have to just get used to it or am I holding it wrong because it's my upper arm that's kind of painful as well as my wrist. It's useable since I have written this entire post using the tablet and I'm learning quite quickly!