Locked-In™ Bar Ends

For most people, a guide on the bar end would encourge dropped elbows because it's hard to get your elbows out without being on the ends of the bar.
Elbows out is a good way to increase control, which reduces arm pump.

But the placebo might be exactly what you need to cure your arm pump, so go ahead of swipe the credit card.

What's old is new again.

Look up Ripco Handleballs.

They sell these for MTB, too. Supposedly the extra contact area allows you to relax your grip a little bit, which would definitely reduce arm pump. I could imagine that being the case, where the karate-chop part of your hand can lock into place a little better. Then again, on the throttle side it may just create a new pressure/friction point that will cause blisters. 

HandleBalls 😂

Just go ahead and do it right. You'll be the envy of all your friends -

Octopus grips.  

Bendz Bar ends are local to my area and I've run them on some bikes. Have them on my KTM300 right now that I ride mostly hard enduro on. 

I’ve got a set somewhere. I liked them. Can’t say they prevented anything but they didn’t cause any either.