Regarding the limitation of the Walrasian model consistent on the assumption that states that all trades are executed at time zero, and in that sense there is no re-trade as time progresesses. The paper available in the link below, shows that supplementing equal individual rights i) to multiple proportional trade, and ii) to mediate, gives an exact characterization of Walrasian equilibrium without transfers. In this case, pareto efficiency is a result of the whole group of agents exercising their rights cooperatively.
In order to hold, this characterization based on Pareto efficiency combined with equal rights to trade, has to satisfy either one of the following conditions: i) there must be only two goods; and ii) at least one consumer has a unique hyperplane supporting the indifference curve at the chosen allocation.
Hammond, Peter J., “Equal Rights to Trade and Mediate”, Department of Economics, Stanford University, August 1999, available on: http://www-siepr.stanford.edu/workp/swp99019.pdf.