WASHINGTON, Dec. 19 -- Law firms assisted companies in the following recently announced transactions: * * * Debevoise & Plimpton LLP... ...advised Vantage Group Holdings Ltd., a privately held specialty insurance and reinsurance company backed by Carlyle and Hellman & Friedman, on its $2.1 billion sale to Howard Hughes Holdings Inc. The transaction involves the acquisition of Vantage by the publicly traded real estate and development company as part of its strategic expansion strategy. The De more ST