Gabel, and all:
It sounds like a small-ish axe is preferred for joinery.
I have a Snow & Neally "Hudsons Bay" camping axe that is a joy to use. (plus, they're from Maine :)) It's head is just 1 3/4 pounds.
http://www.snowandnealley.com/products/axes/hbca24.htmI use this axe regulary for splitting firewood and find I like a lighter weight axe. Splitting wood is great fun and has turned into a zen-like practice for me: reading each piece of wood to gauge how it will split, etc. I'm guessing it's much the same w/ a tenon. I love it when the piece I set on the chopping block absolutely explodes, but the effort was not overly strenuous-- the axe is left firmly in the block. When I can just leave it there; releasing my hand automatically in the pride of a near-perfect action.
I'm becoming more proficient w/ practice, (one-handed at times) and it sounds like you are refining your technique as well w/ tenons/housings, etc...
Axes are very cool.