First, If you're making it through the game, you're doing fine. Don't worry about having a "best" build. That type of discussion can get nit-picky, requires tons of out-of-game knowledge and has a lot of subjective player preference in anyways.
It looks like you're going with a Shield Agility Build for Gris. Makes her a solid tank for your mage to hide behind (err... I mean tactically position to optimize overall combat effectiveness). That lets you take full advantage of light weapons, such as the Icicle, an unusually strong weapon or when you can get it.
Your skill set is spread out nicely. I have mixed feelings about Resilience. I tend to skip it, but if it fits your build pattern well, feel encouraged to keep using it.
Tombs: There are plenty of times when using a Tomb on your Companion makes more sense than saving it for yourself. At the upper levels, you might find yourself with unusable trait points (too few for any trait). Or even if you could use them, it might make more sense to boost your Companion. Just be careful you don't use too many on your Companion least you regret it. So, try it out?
The Heavy Hand Question: Gris gets the Advanced Skill Heavy Hand when you complete her Companion quest. However, it requires STR 4. So even an Agility Griss benefits from getting her STR to 4. Heaby Hand offers the highest consistent damage output of any skill. Also, since STR gives a boost to health, it pairs well with Body Development. Get those extra HP.
But as Mage, you might be totally okay in the offense department so maybe you prefer keeping Gris defensive. Infantry Training might pair well with the Body Development you already learned.
This discussion is based around keeping the basics to your build intact. Going 2-H Late Game is a different discussion. But who needs defense, when Gris can just stun the heck out of everyone with 2-H Expert?