Kinsbaile Cavalier

Knight creatures you control have double strike.

Glen Elendra Liege

Flying
Other blue creatures you control get +1/+1.
Other black creatures you control get +1/+1.

Silverblade Paladin

Soulbond (You may pair this creature with another unpaired creature when either enters the battlefield. They remain paired for as long as you control both of them.)
As long as Silverblade Paladin is paired with another creature, both creatures have double strike.

Lightning Greaves

Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)
Equip {0}

Duelist's Heritage

Whenever one or more creatures attack, you may have target attacking creature gain double strike until end of turn.