Hey Wolfen,
I have a similar build right now. My party is currently at level 7 with the following:
Lone wolf fighter, 9str,6int. Man at arms 3, Hydro 2.
Ranger w/ 1pt each into Geo/Witchcraft/Scoundrel. 3 in Marks
Jahan w/ Pyro 2 and fire spells added
The first guy is a bit like yours, but is more solder-heavy. Between a couple spells available early in Hydro, and cure wounds from ManAtArms - I have a ton of self-cast healing. I start a fight with a 2handed weapon and if things get fishy I can switch to shield and use two heals in the same turn. It's really fun! But it might be a little more melee-heavy than you are going for if you're looking for caster heavy. But he can cast rain, two heals, and ice shard effectively without ANY base points into intelligence. Sometimes my +Constitution spell fails, but not often enough that I stop using it.
I think if you want to do an armored caster, without any focus on melee, you could definitely go for 8str8int to wear decent armor/shields early on. Then just decide what magic trees you want to 'mainspec.' I am thinking about getting my Jahan a shield if I can find the proper +str items longterm.
As Scrotie said and I have learned, when you are shopping past level 6 you will see ability books that are like "wow that sounds good, do want." So save your ability points if you aren't sure what you want next. Then you can pop the points into 1-tree to use a very special book you think will work well with your playstyle.
