However, according to the card text "Stolen Steel", I would expect to actually steal a weapon.
A better card effect might be "Steal a weapon from your opponent. If he has no weapon, summon a random one (from another class)". But it is probably too strong, especially for 2 mana, and a deckkiller against Kingsbane Rogue.
Interesting card. My first idea was to use this card in standard Zoolock. There it should have the greatest potential.
But on the other hand - this card should also work pretty good in combination with any deathrattle cards like Devilsaur Egg or one turn after playing Bloodreaver Gul´dan, when the board is full of Demons.
I dont think this card will have a high potential. In most cases Druid will not have enough attack to make a benefit out of the card. Moreover, there exist enough draw cards for Druid, e.g. Branching Paths, Ferocious Howl, Nourish, Wrath, etc. that have (or can have) an additional side option (get mana, deal damage).