how do i make it so objects wont share the same texture?

i import .3ds models from blender to unity and i am aving trouble with the textures on a sword sharing part of it with a tree so how can i change it so that it wont refrence the same texture

To avoid a problems like this you would have to make several different materials with the same texture. This would make it so that only that specific texture in that materials changes not all of them.

I would suggest to simply UV_Unwrap your model in blender and then to texture it using something like gimp or photoshop.I do this my self as personally it gives a much greater control over your textures.
There is loads of tutorials on youtube that show you how to UV_Unwrap your models and how to make textures with both gimp and photoshop.Just to note gimp is free to use.

If you don’t want to do that then what you could do is separate your model in blender into different parts and apply textures to each of them individually.

Hope this helps.
Peace!