On Ketuvot 86a - Rashi explains that according to those who do not adjucate liability in a case of indirect damages, in the case of sale of valid bonds, which the seller later waived, the seller is liable for the paper value only because the seller could say "I only sold you the paper"? Isn't that obviously untrue? The sale of the bonds was clearly NOT the sale of paper.
On Bava Kama 46a the issue of evaluating whether the sale of an ox was for slaughter or for work, the first suggestion of the Gemara is to see whether the purchaser is one who purcheses for work or who purchases for slaughter; and the Gemara says that the dispute whether it is a Mekah Ta'ut is only where the purchaser purchases for both slaughter and for work. Here, however it is perfectly clear that the purchase of the bonds was NOT for the paper.
This case should not be confused with the case on Bava Kama 33b where a person damaged the bonds, and Rabbah limits the compensation to the value of the paper - in that case there was no purchase. Besides - in our case the seller should be liable for a 'Takant HaShuk' - to enable the trade in bonds! - Or even more important: when a creditor needs money and wants to sell his bonds - it is the interest of lenders that the creditor should be able to do so easily "Shelo Tina'el Delet Bifnei Lovim", and if that is a valid purpose - the sale must be secure, and in that interest the waive of a sale secured by a bond should be invalid, or at least the waiver should be made liable, at least Mid'Rabbanan!
Yeshayhu HaKohen Hollander
There is no question of intent in the sale of the Shtar. Of course the sale was intended to include the debt as well as the paper.If the seller does not waive the debt, he clearly cannot claim that he sold the paper alone.
The reason that he does not have to pay if he is Mochel is the same as one who burns someone else's Shtar. The reason he is ABLE to be Mochel is because although he intended to sell the Shtar with the Chov, it is impossible to make a Kinyan on the Chov itself and therefore the ability to be Mochel remains by the seller. (See Insights)