There isn't any need to invest in any other stat points other than your class's main stat point (i.e. dhan - agi, guard/noir - str, temp/lock/ds - int, ranger/scout - dex, rumir/priest/wiz - psy, etc).

Once you have mid-endgame gear (opaniels or abyss for example), you will have enough all-stat points so you never miss (dex-related), have craploads of resistance (int/psy-related - can't remember which), have tons of hp (vit-related), and a substantial amount of mana (psy-related) without having to invest any single point to any of those.