Hey, Make-n-break! I saw this bow survived in the other thread. I have a few ideas for you, since I have tried so many similar things just to see WHY it won't work. :-)
If you add a handle like that, either with just a board or two butt spliced boards like you did, and want to add dowels, ANGLE the dowel holes. My best luck has been to angle them just a little, from close together on the belly near the handle, toward the tips as you come out the front. Like this. \ \ / / if we say the back is up and handle is down. On a board to handle set up, this helps lock them down mechanically as the bow bends. On butted boards it seems intuitively that opposite would be better, though.
Also, instead of butting them, you can very easily do a simple slash or diagonal splice. Just gives each board more length on the overlap. It really improves the strength (though you proved maybe we don't need it,) You know how to handle fades, of course, and a front overlay helps and looks good, too. You can flip one board, stack them, and clamp them and make the same angle cuts at the same time. Of course, you need that extra 3-4" in board length to begin with.
Lastly, when you get that handle shaped, I have a couple times wrapped the handle splices/joints with baling wire, then added the twine wrapping over the top of it.
