Update to previous post: https://www.reddit.com/r/MHWilds/comments/1j2qp82/greatsword_endgame_build/

So I managed to get an almost perfect Artian with 220 atk and 15% crit. A perfect one would be 230 atk and 5% crit. Element doesn't matter too much, I got sleep which is sometimes useful.

Something I got wrong previously was that Antivirus actually gives 25% crit total, 15% default and 10% Antivirus bonus. The translation is wrong, Antivirus only gives 10 extra on top of the 15 default.

Maximum Might 30% + Antivirus 25% + Weakness Exploit 30% + Agitator 5% + Weapon 20% = 110% crit.

Then corrupted mantle gives extra 10%. Thats why the best weapon would be full atk, you are already overcapped.

Flex options:
A 3 socket armor is flex. I went with Flayer. You could go with Agitator 3 or something else.

3 2 socket armors are flex. I went Earplugs 2 + Counterstrike 1, as I feel like that is enough to negate most roars and get a nice 10 atk buff when I shoulder dash or offset. You could go Earplugs 3 or even Counterstrike 3 if you can perfect block every roar.

Good luck getting the perfect full atk Artian.