I can introduce no new physical characteristics using a non physical descriptor? Because 'soul' is actually descriptive of something.
As you've pointed out, all the characteristics you've associated with 'soul' cannot survive death, and therefore cannot logically be attributed to something which by it's nature survives death.
As you've pointed out, all the characteristics you've associated with 'soul' cannot survive death, and therefore cannot logically be attributed to something which by it's nature survives death.