It makes you appear more flexible. Divulge true interests to other party or someone else. Either party can veto the new agreement. Both parties share in the increase. Find a more efficient agreement by finding hidden value.
Unclaimed value lies in the different value people attach to interests.
If one party believes that some important event has a high probabilty of occurring whereas the other person believes it either to be of low importance or low probability, then make each event part of on an option. Make many issues from one. Other party gets higher upside potential. The guarantee helps solve the risk problem and could be a good deal for a more risk seeking person who thinks there is a good chance for high profits. Reframe loss descriptions into gain descriptions.