You can use the chart on this page
http://lucy.allakhazam.com/dmgbonus.html?setcookie=1 to determine how much to add to your 1h and 2h weapon for bonus. It depends on your level, at level 50 ebon mace has better ratio, at level 60 30/40 weapon is better. Assuming the chart is accurate.
At level 50
ebon mace would be 19+8/24 = 27/24 = 1.125
30/40 two handed weapon would be 30+14/40 = 44/40 = 1.1
At level 60
ebon mace would be 19+11/24 = 30/24 = 1.25
30/40 two handed weapon would be 30+34/40 = 64/40 = 1.6