DM question about a Captain America character.

I'm the DM, and I've got an Eldritch Knight player who wants to be Captain America. He's bonded his shield, so he can use a bonus action to teleport it back to his hand, and wants to know what its stats are should he decide to throw it. I'm thinking 1d8+Str and a low Strength check on the target to see if they're knocked prone. Is this OP? Will I regret it? He's only level 6 right now.