To the OP.
Your idea of a roguish fighter mage looks great.
I think it is perfectly doable as a Lone Wolf, and I would do it with the build below.
First of all, what you will have as attribute, ability and talent points to spend:
Attributes: 16 from 5 at start + 10 through level up + 1 from the Seller of Secrets (or more if you want to buy one book at every level. FYI, you should reach it at around level 9 if you spare a few side-quest xp, thus 12 additional points, splitted with your teammate that should give you an additional 6 points).
Abilities: 71 from 5 at start + 44 through level up + 19 from Lone Wolf + 3 from the Seller of Secrets (or more for the same reason. That should give you an additional 18 points).
Talents: 7 from 2 at start + 5 though level up.
Then the Abilities you want:
With Man-at-Arms 3, you will have access to (amongst others):
Note: in my opinon, the current Man-at-Arms ability is a bit broken as there is little incentive to level it very high as skills don't get better whith a higher ability level.
For instance, your (very good) starting skill Dust Devil will be the exact same with Man-at-Arms skill level 1 or 5, with the same cooldown and the same damage. Damage depends on your Strength, your weapon and the corresponding weapon skill. That means that you could end end thinking that Man-at-Arms level 3 is perfect enough. Sure you won't have access to the Weather of Storm talent, but with your plate armor and a couple of rubies, you should be fine enough.
With Air level 3 you will have access to (amongst others):
Plus the ability to create static cloud and electrified surfaces and remove all kind of surfaces (Tornado).
Then the abilities I recommend:
With Witchcraft level 3, you will have access to the famous Oath of Desecration and be able to do nasty things (rogue for the win) like removing 5 Willpower points from an enemy or mass weaken a group of enemies. You will also get some nice summons.
With Water level 1, you will have access to a basic heal when your other options are on cooldown, to Rain in order to shut those fire surfaces down and to Water of Life which boosts your Constitution.
With Pyro level 1, you will have access to Wild Fire for a very nice haste effect and Flare in order to set those oil surfaces on fire.
Note : all the above abilities will make your investment in Intelligence more worth it.
With Willpower and Body Building level 5, you will get all the resistance againsts statuses you can get.
As mentioned before, this is recommended in a two lonewolves party.
With Leadership level 3, you will boost your teammate with very nice bonuses (initiative, damage, chance to hit, crit chance). That would be nice if he/she could get the same bonus for you
It should be noted that Leadership bonus can come on various items and I would not be surprised you would end up with Leadership 5.
The following are optional but I recommend them because you need to spend some points on non-combat abilities in a two lonewolves party.
With Blacksmithing level 3 and Crafting level 2, you will be able to max both with some bonuses on spare gear you keep in your bag and the right Trait (Pragmatic). Your teammate will be happy with your ability to max all his/her gear out.
All of this for 65 ability points.
You will then have 6 remaining points that you can spend in your weapon of choice, Two-Handed or Tenebrium (or one after the other if you want to respec) up to level 3.
As an option, and if you don't want to spend all these points in Blacksmithing or Crafting, I recommend you invest some points into Sneaking. Not much, like level 2, as you may get some bonuses on your gear or add some Void Essence to it. That would make your character more roguish, and with the right Talent (Guerrilla) you could do huge damage each time you can sneak before landing your two-handed blow.
Then the Attribute distribution:
For Intelligence, all the recommended mage skills above require 10 at max.
No need to push it more as all these spells are not damage oriented.
It is pretty easy to get a bonus of 2 from gear (Amulet and Sarong), so you should aim a base of 8 Intelligence.
I would start at 7 and add a point later and would be set.
3 points required then.
For Constitution, as a Lone Wolf, you should not care much regarding your vitality. You will have plenty, even in Hard mode.
However, if you plan to take the Glass Cannon Talent, then it could be another story and you will have to invest some points in there.
Not only for the added vitality in order to compensate a bit the loss from the talent, but also because you want to raise your Max AP.
You should also favor gear with added Constitution in this case.
Don't forget you have access to the Water of Life spell!
I would start at 5 in any case.
x (Glass Cannon) or 0 points required then.
For Speed, it depends on wether you are going to take Glass Cannon or not.
If yes, then you don't need much as you will double your AP recovery.
I would start at 6 and raise it by one point later (It is not uncommon to find speed bonuses on rings and boots).
If not, then I would start at 6 as well, but I would invest more points later.
2 (Glass Cannon) or x+2 points required then.
For Perception, I am afraid you will be pretty bad at it.
Choices have to be made because Lone Wolf, for some reason I don't get personnally, doesn't provide you with more Attribute points.
I would start at 5 and expect some bonuses on gear, like on helm for instance, and maybe on your weapon if you're lucky.
It would be nice to have the Fire ability at level 2 for the nice Burn My Eyes spells which boosts Perception by 2 but I could not find the needed 2 ability points.
Of course, if you think you will buy these books at the Seller of Secrets after each level up, then the problem is over.
0 point required then.
For Strength, you should aim, well, the max, i.e. a base of 15.
I would start at 7 and would invest all points I don't invest in Constitution (Glass Cannon) or Speed (otherwise).
16-5-x points required then, up to 10.
The total must be 16 Attribute points, unless you buy more than one book at the Seller of Secrets.
About the Talents, I leave you make your choice