It's a
totally useless spell...
....and then I found a use for it.
My current PC is built around
armour of agathys while taking half damage while Raging. He started out Bar 1, then took War 5 (fiendish bladepact), is now taking it up to Bar 3/War 5, and then warlock all the way.
The usual tactic is to cast a pre-asskicking fireball and then Rage and move through mooks hoping to get attacked. But what if the baddies are sniping from across a chasm or something? Sure, I've got a bow, but I really want to get up close and personal. So I
misty step to them.
The trouble is that I can't cast spells while Raging, so I cannot Rage first and
then misty step. Nor can I
misty step and then Rage on the same turn because they are both bonus actions.
Solution? Cast
blade ward as my action and then
misty step as a bonus action. I'll take half damage while they take 15 cold every time they hit me. If there are enough survivors, then on my next turn I can Rage and attack twice with my soul-sucking magical greatsword.
Good times.
So, finally (and unexpectedly), a use for
blade ward. I took both it and
misty step at War 4.