Abdel's Trusted Shield
Abdel's Trusted Shield is a very rare Shield that allows the wearer to cast Protection from Missiles once per Short Rest.
Attached to this shield is a faded note. 'G, I've found the best defence against an arrow is to be the one behind the bow - but this shield also does the trick in a pinch. Yours, AA'
Properties
Required Proficiency: 
Rarity: 
Weight: 2.7 kg / 5.4 lb
Price: 570 gp
Special
The wearer of this item gains:
Shield Bash: When a foe hits you with a melee attack, you can use your 
Reaction to knock them Prone unless they succeed a Dexterity 
Saving throw.- Gain the ability to cast
once per Short Rest.
Where to find
Rewarded from Golbraith in the upper level of his home X: -148 Y: -60 in the Lower City, after convincing him of your courage against Mind Flayers.
Notes
Apparently, Golbraith was a friend of Abdel Adrian, the main character of the previous installments of the Baldur's Gate series. Some details about this can be read about in the book Confidant of a Duke found on a bookshelf beside Golbraith. However, neither Golbraith nor this shield appear in any previous games.