Devcon 2 Ton epoxy can be very temperamental stuff. It's curing rate can be abbreviated by a few different things such as heating the bait or the epoxy itself or the humidity and temperature combination at the time it is mixed.
Furthermore, the stuff seems to cure at a different rate as it ages and it seems to have a finite shelf life.
It sounds to me as though you mixed it too long and it began to set up quickly as you were applying it. I know because I've had similar experiences. Your natural reaction is to try to "brush it out" right away but you only make it clump up worse and it hardens even faster. Once it starts there is no way to slow it or reverse it...its just a mess. You could heat it till the bait catches fire and the stuff will not smooth out once it gets to that sticky, lumpy, clumpy point.
All is not lost, however. You can, if you wish to put the time into it, sand it down carefully and put another coat on over it. If you patiently sand out the high points, the next coat will tend to smooth things over. You can actually be pretty aggressive in your sanding technique since it is the high points which will tend to be sanded off first and not the lower coats or the paint beneath. Of course, depending on how delicate the bait is, you have to determine whether or not it can actually tolerate another coat without affecting the action. But if its ugly (lol, like mine were when it happened to me), you've really got nothing to lose. I hate using any bait with any major aberrations or flaws in it. If I can correct them, the flaws bug me the entire time I'm fishing with the bait.
I was also strongly suggest that you consider buying a new tube of and when you do, try to buy Devcon with the least amount of yellowing showing on the hardener side. Light and time seems to cause that yellowing and in my experience, the more yellowing you have in the tube, the shorter the working time and higher the propensity for yellowing after the epoxy is actually applied to the bait.
Personally, I've pretty much moved completely away from Devcon for final clearcoating for a variety of reasons, which I won't go into here. I will say this: I'm a lot happier using it only to glue in the screw eyes and the lips on my crank baits.