During quest at the cementary, my new mage companion keeps forgetting that he is a mage.
He keeps fighting melee, with poor results. How force him to cast spells? Virgil has some magic and he casts it with no problems, so i dont really know what is the problem.

I don't know if there is a way to make him use any of his spells. I have really not played much with him, and I have found him fairly useless. I think once he gets his summon ability (in the Necro Dark tree) he summons the undead sometimes.

But the spell casting AI in Arcanum is particularly bad unfortunately and I don't think there has been anyway to actually fix it (the game has been out for like 10 years, if there was a way it probably would have been done by now). Mages are good at using their healing spells, and summoning spells if I remember correctly but everything else is basically right now. :(

There is no way, I am afraid. Never had Geoffrey in the party, but other mages all behave the same from what I remember: either waste all their spells on the first mook and then go into fisticuffs or go into fisticuffs right away. It's just borked AI. Virgil is spared from this because he is strictly healer with no offensive spells.

Damn.. I will have to get other non-magical companion. Thanks for answering.

iv noticed that when you take control of that lava spider (the one that effs up you party with three fire flashes in a row) he never uses magic once you control him he is only good for doing fire damage. although... iv only taken control of them in turn based combat, they might do different in real time

I have found the mages to be very helpful. Played a halfling having at the end of the game a strength of 2+Blessings and they cleared the void like nothing.

But I wonder what the problem is with Geoffrey Tallerond-Ashe. Even Simeon Tor told me that he would not be the kind of companion I should go with. But why? Is there any background information available somewhere or is it just like that?

A PC mage isn't just helpful, it's crazy overpowered. Companion mages, however, suck. As for Geoffrey, is your PC good aligned? Geoffrey is evil himself and would only join evil characters, I guess the warning is about that.

I am more evil than Geoffrey. With the dark helmet I have lowered alignment for everybody in the group to be -50 or less. Nasruding told me: You are far two evil...

NPC Control (or lack thereof) is the absolute low-point of the entire game.

Just saying.

My experience (only one play through) was that mages in my party would very rarely bother casting spells, other than Virgil and his healing. I had a dwarf that had all of the force (lightning) spells including disintegrate... and the only time he ever cast one was when I abandoned the rest of my party, removed all his gear, and trolled around the map seeking out random encounters for about 10 mins. Once, he used jolt. Never used it again in the remaining 10+ hours of the game though.

Raven actually cast a couple of "summon water elemental" spells (and some kind of rain spell?) very late in the game against some high level enemies, but that's it. Even when I removed all of her weapons, she went hand-to-hand (same deal with the dwarf).

Now if you want a useful follower (who's even free in terms of your follower count), seek out the dog.