Hello @JeremyECrawford. A magic shield +1 used like a improvised weapon will add the +1 to the attack and damage rolls? Thank you.
— Jefferson Oliveira (@jeff_kiadar) September 6, 2016
A +1 shield gives a bonus to AC. The bonus has no effect on an improvised attack roll you make with the shield. #DnD https://t.co/D8E7vV96cy
— Jeremy Crawford (@JeremyECrawford) September 9, 2016
@JeremyECrawford @jeff_kiadar would it still count as Magical for Resistance/Immunity to non-magical B/P/S attacks?
— Daniel Dettinburn (@drakus1111) September 9, 2016
A magic shield is not a magic weapon, unless its text says otherwise. #DnD https://t.co/iYKkELFznD
— Jeremy Crawford (@JeremyECrawford) September 9, 2016
If it’s magical, and can be used as a improvised weapon, then it’s a magical improvised weapon.
My interpretation of an improvised weapon is that it’s not a weapon but is being used as such. This would mean that a magical improvised weapon still isn’t a magic weapon since it’s not a weapon.
That being said, of course you (or your DM as appropriate) can rule otherwise.
By that rationale, a potion of healing, being magical, becomes a magical weapon when you smash it over someone’s head as an improvised weapon.