ABU DHABI, Jan 11 (Reuters) - National Bank of Abu Dhabi , the United Arab Emirates' largest bank by assets, has appointed Omar Mehanna as managing director and global head of merchant banking, the lender said on Sunday. Mehanna will be responsible for the corporate finance, equity capital markets, project finance and debt advisory platforms, as well as developing NBAD's merchant banking proposition, according to a statement from the bank. He joins NBAD from Saudi British Bank, where he was chief strategy ******r. He also previously worked at HSBC and Bank of America. ...