Your character looks like out of a game, but I am not sure about that.
What's definitely off is the posing.
Nobody would hold a sword like that, especially not if one's about getting serious.
the tip Tip should get up, you might want to move it in the hand closer to the front of the fighter, the weighting should be distributed like 70/30 to enable quick movements. A lot of that depends of course on the attack style.
I'd suggest that you either look for general reference of swordfighting poses, fencing or similar stuff. and try to find where the positions of the feet are, where the hip shifts in order to support the weight, and where and at what angle the sword is hold.
If you need video footage searching for "HEMA" (Historical European Martial Arts) - that should lead you to some really interesting and accurate reenacted swordfighting poses with motions for attacks and parades.
There is pretty good material around for arming swords, longswords, sabers and also Langmesser - most of it is shown without armor, but there are also vids on how platemail restricts the movement for several techniques.
While a game of course doesn't need to be 100% realistic and should rather push the gameplay aspect, than the exact simulation.
For art it's generally not bad to learn about poses, capture them and maybe even exaggerate them in order to get it look alright in the context of an image, and even more so in the context of an animation.
