Do you have Flex? If so, make a Springboard patch, process SpringBoard executable, search for SBLockOverlayStyleProperties method: -(double) tintAlpha and SBLockOverlayStyleProperties method: -(double) blurRadius and set both values to 0.
A lot of these blur and tint values can also be altered in the hidden SpringBoard settings menu if you have any tweaks that reveal it.