After i putted skill-points into "raise sk. mage" i noticed something very strange.

They gain no life whatsoever

I started some research with a hex-editor, opening skills.bin, and i cant find any self synergy for additional hp%/lvl bonus for sk. mages, while the value is set on 30 inside skills.bin.
HEX=1E => 30 decimal, for both param2 & param5
param5 is correct and used for ac/lvl (defense/lvl)
param2 is used for calc1
origin formulae for calc1 (hp% adjustment) in diablo2 v. 1.11b is: (lvl < 4) ? 0 : (par2 * (lvl - 3))
wherin par2 = 30
in other words:
They keep having 61hp while putting in points into the skill...
They only get additional hp from mastery, 8hp/lvl

, as the normal fighters do also.
Or i'm terrible wrong and the skilldecr.txt do not match the skill-decription window inside the game, in any case this is a bug.