In general with RPGs it almost always a mistake to spread your attribute points around because you become a jack of all trades and master of none so you lack the firepower to tackle strong enemies and bosses.
In this game (as with OB, Skyrim etc) you are single character so it is difficult to ignore certain attributes that appear necessary/desirable to have, but the games are designed and balanced so that you cannot be good at everything, you have to specialise in certain things using them to maximum effect and work out how to overcome your weaknesses in other areas.
In this game DEX is problem if you are playing a warrior, mage or warrior/mage since it governs both your ranged defence rating and the amount of extra damage you do on critical hits IIRC. Both are very desirable attributes, but you have to ignore DEX to solve those problems if you play this type of character.
Also in this game most charcters benefit from using magic to some degree (same as OB/Skyrim) but you should decide if you want to play a primarily weapon based or primarily magic based and distribute INT and STR accordingly rather than put the equal amounts in both. What is different in this game is that many weapons do primarily magic damage which is governed by INT so it is possible for a character with limited strength to do significant damage with the right melee weapons and do a great deal with magic.
If I was a warrior/mage I would put 2 pts each in VIT and STR for two levels and then 2pts VIT and 2pts INT for the third.
If I was a mage/warrior I would put 2pts VIT and 2pts INT more or less every level and use pure magic weapons. I suppose that's more of a pure mage really but that's how I would do it.
