By the looks of it the FABRIK is pulling the ik towards the ik target so the problem is with the offset between the left hand joint and the hilt.
To be able to give some informed advice there is a need for a better understanding of the purpose that needs to be served as part of the overall design.
Usually the lack of purpose is the reason most posts like this goes unanswered as there is more than a few different ways of doing the same thing with the better option being more of a guess.
- Is the sword weapon unique to this character?
- Does the character use other weapons. If so what types.
Guessing the easy way in this example would be to just move the hilt target until it matches up with the hilt.
The other option would be to add a socket to the left hand and use it to add/subtract the offset.
From a keep it simple standpoint I would be inclined to add the sword as part of the character component