Display settings of .obj weapons

Hellou guys,

I have a problem, and it is that when importing my custom weapons in .obj format they are displayed incorrectly within the game.

In the third person, for example, the swords are displayed correctly and the character appears to be holding them in his hand, but in the first person the perspective is incorrect and the sword is horizontal instead of vertical.

Is there a way to change these parameters? For example with .json files I know that you can choose each point of view (left / right hand, ground, item frame, hud etc.) but I can't find a way to do it with this format (.obj)

PS: They are made on Blender, so I can't import them in to Blockbench or use .json

Thanks for your help ~