The stat system upon initial release of the game was broken and incomplete. Currently based on solid parse results, DEX provides no gain as far as critical hits & accuracy is concerned. Piety has an impact on the ability of DoTs (from spells or weapon skills) to stick. STR does have an influence, but it is very minimal. Vit/Mnd are important for keeping your HP/MP up, and MND on an Melee class actually increases your survivability tenfold provided you have your protects/shells/cure IIs/sanc IIs.

So yes, stats are broken and anything pumped into STR/DEX at this point in time is moot. Once the battle changes are implemented this Spring, I'm sure you will see stats being fixed along with them, or near-to. For now, pump your VIT & MND as they will be the factors in helping you survive.