Best solution to stop battery drain is turn every thing off if you're not using it eg GPS, wifi, Bluetooth, mobile data, auto sync, if you have them on they will chew up power.
On a stock legend, HTC would seam to have the CPU speeds set at 480 low and 600 for high, if you root and set your lower value to lower than 480 that will also help in cyanogen lowest value is 245.76, this seams to be ok, on other roms they can go as low as 19, this is not so good as phone can sometimes freeze. I never go below 122.
sent from my legend, currently using extream legend fuse™
Update: 17th november 2013
Samsung G S4 stock BMG4 + root
with cf-auto root + philz recovery.
HTC Desire HD
(Hboot 2.00.0029 AND S-OFF)
SVHD V 2.1.0
Retired HTC Legend