I don't think you need to use Blender to make this change. All you need to use is ARCtool.
There are no models specifically for figures, they just use graphics from the game. Therefore, if you change the character's .arc, the figure's appearance will change at the same time.
By the way, the pose data for the figure is in the ".lmt" of the "fig○○.arc".
About swapping models.
For example, if you want to swap Chris BSAA for Wesker S.T.A.R.S., first unzip "uPl00ChrisNormal.arc" and "uPl03WeskerCos2.arc" with ARCtool.
Next, copy the "pawn" folder from "uPl03WeskerCos2" and paste it into "uPl00ChrisNormal". Now open "uPl00ChrisNormal/pawn/pl/pl00/model" and delete "pl0000.mod". Finally, copy "pl1600.mod" from "uPl00ChrisNormal/pawn/pl/pl16/model" and paste it into "uPl00ChrisNormal/pawn/pl/pl00/model" and change the file name to "pl0000.mod".
Then just repack it and apply it to the game folder.
Now you can change the figure's appearance.
If you want the model-swapped character to move in-game, you will need to make changes to the "motion" and "soft" folders.