D&D 5e: Buckler Shields

+Tabletop Gaming with Juce  recently wrote a post about buckler shields. I liked his ideas, but in my opinion his mechanics made bucklers a little bit too useful for certain class builds. Here is a variation based on how I think buckler should work in D&D 5th Edition.

Buckler Shield

Source: Matka Boska Armoury

AC:  +1 (when used with no armor, light or medium armor only)
Cost: 8 gp
Weight: 3 lbs
Damage**: 1d4 bludgeon

A buckler shield is a small shield held in one hand or strapped onto the user's forearm. Heavy armor users do not receive an AC bonus as heavy armor already includes heavy gauntlets and vambraces. ** A buckler shield counts as a light melee weapon for the purpose of Two Weapon Fighting and does 1d4 bludgeoning damage when used this way (a DM may optionally allow a spiked buckler to do piercing damage). Due to their small size, buckler wearers do not gain the benefits from the Shield Master feat.

Source: Matka Boska Armoury

An alternate version is more like a forearm shield, not a round buckler, so would allow the user to still use a "free hand" in a limited fashion. As a DM, you may choose to disallow this use if you want the more traditional small round buckler.

Optional "forearm buckler" mechanics:
A class with martial weapon proficiency may also use a light, simple weapon (club, dagger, handaxe, light hammer) in the shield hand. The buckler gives the user limited use of the shield hand to hold or retrieve items (although an item may be broken or dropped if the user needs to use the shield for defense in the same round).

The buckler wearer gets Disadvantage with any thrown weapon using the hand holding the buckler. The buckler wearer may also use a two handed weapon or bows/crossbows with Disadvantage.

Feedback or alternative ideas always welcome in the comments.