The negotiation strategy selected may still be a generalized strategy that has to be instantiated by giving values to some variables of the strategy.
The main reason why an agent would have generalized strategies is to save space. The agent may need a few different strategies for a type of conflict, and if these strategies are very similar except for a few minor points, then it is better to have only one generalized strategy rather than storing all these similar strategies separately. The generalized strategy can have variable parts to allow for the differences in the group of similar strategies it represents. The generalized strategy can then be instantiated using some criteria similar to the ones in strategy selection.
Another reason why a generalized strategy may be useful is if the agent does not have enough information to select a strategy before the negotiation starts. In this case, the agent can start negotiation using the generalized strategy and then instantiate it during the negotiation as more information becomes available.