Completely unnecessary. When I make a bow that needs a piece added on for the handle, I add it to the core which is the same thickness as the inner limbs, no pedestal or powerlam, and they never come apart. Good glue, good surface prep, and good design is what ensures a good bond, which will be maintained even if the area flexes a little.
First I mate the pieces as best I can. I'm pretty anal about a good fit. Then groove them with a toothing plane blade, held like a scraper, creating grooves the full depth of the teeth, the length of both surfaces to be glued. Then glue with Smooth On EA 40, clamp, and set a shop light near it for warmth. With the grooves from the toothing plane blade, it's practically impossible to starve the joint of glue.
Now, just because we create a very good joint doesn't mean we should do a lesser job of coordinating the flares and dips, or blending the dips into working limb. Imo, many folks could do a better job of it. So make them flow into one another seemlessly, so from the side you can't tell where one piece stops and the other begins, and so the dips gradually slow the flexing of the limbs. It's the fear of them flexing, and the fear of the handle popping, and perhaps impatience or lack of finess in this area that causes many folks to shape them in such a way that they halt the bend too abruptly, ironically increasing the odds of separation.
