Whoa, Zen! Good to see you again man
The hydra sacred bug is fixed by the special hydra quickfix mod. As for the cataphracts: they just arent special enough of a unit to bless, not to mention thier excessive resource cost.
Yeah, I toyed around with an S9 or even S6 blessing but its just not worth it for the amount of points you have to put in. Hydras have good MR anyway. In the end I think I'm just going to go for a combination of low level blessings to give the hydras a little more oomph and concentrate on scales and magic instead.