Equipped creature gets +2/+2 and has protection from white and from blue.
Whenever equipped creature deals combat damage to a player, put a +1/+1 counter on a creature you control, then proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
“‘The name of it,' said the lady, ‘is Excalibur.'”
—Sir Thomas Malory, Le Morte d'Arthur