I always figured Desperate Blows worked like Dual Wield. It modified the delay before applying Haste.
If this is true, then Desperate Blows would be a good thing to merit, IF you have a good haste built in the party. Normally, people use RDM haste, but not BRD in exp pt. So with Desperate Blows and Haste, that would be 30% haste...
Add on some common equipment builds, like Walahra Turban, (5% haste) Swift Belt, (4% haste) then you would have about 39% haste... for 30 seconds.
That would lower the Delay to about 318 (if the scythe is 520 normally)... Not bad at all, but for 30 seconds only? GAY! lol. Most GS's would be lowered to 300 delay.
BUT! Lets look at what a Maximum haste build could do!
25% cap
Rune Chopper - 9%
Walahra Turban - 5%
Velocious Belt (or speed belt) - 6%
Dusk Gloves - 3%
Dusk Ledelsens - 2%
50% cap
Haste - 15%
March I/II - 9/11%
Haste Belt - 15%
15% cap
Fully merited Desperate Blows
(cyclopedia isnt loading for me, so Im gonna assume the Chopper is 500 delay)
This build would practically make you attack with a Great Axe about as fast as a Sword will. Kinda nifty... But not practical in exp