More on topic now...
The first thing you want to max on any turian is the weapon / power passives, because it's absolutely great. Overload (preferably with the shield damage evo at rank 6) and Warp are two excellent powers too, so it is advised to max them too. If you feel that you need more points for fitness, skipping the last rank of Warp is OK. About the split between fitness and Tech Armor, I would say that going past 4 ranks in the later hasn't great returns. Besides what capn mentioned, boosting the power or melee damage at rank 5 hasn't many uses with this character. Rank 6 isn't that good either. So 4/4 between fitness and Tech armor seems the way to go, though it depends on what armor bonus you put on him. If you use a high level cyclonic, then I would say that 5/3 is better (recovering fast high shields is very valuable), otherwise take the 5% additional damage reduction.
You may have already noticed that, but the Tech Armor's detonation has a very high force. So it can stagger many enemies in the game, including Atlases. It can for instance save you from a Phantom's sync-kill : if she starts meleeing you, detonate your Tech Armor, it will prevent her from finishing her death move.
About the weapon to use, there are plenty of good choices, because the turian sentinel make them almost all good. I personally use the Lancer (got to take advantage of that stability bonus), but the Arc pistol is probably the most popular on him. Just avoid to be excessively heavy, because spamming Overload is both an excellent first move to attack and a great defensive ability.
A last remark : don't expect too much from the tech bursts with Overload + Warp : they're extremely weak.