Can a Battle Master Fighter use a shield to parry?

Question

A Battle Master Fighter was disarmed of their weapon and had only a shield. On the next attack they wanted to use a superiority dice to parry:

Parry: When another creature damages you with a melee attack, you can use your reaction and expend one superiority die to reduce the damage by the number you roll on your superiority die + your Dexterity modifier.

Being they had no weapon to parry with I ruled they would not be able to use that maneuver. Been replaying it in my head and I feel like I made a mistake but can't find much on this issue.

How should this be ruled?

Answer 1

Yes, the Parry maneuver can be performed without a weapon.

Your ruling contradicts how this class feature is written. The Battle Master does not require a weapon (or even a shield) to perform the Parry maneuver. The only prerequisite conditions are (1) the fighter takes damage from another creature's melee attack, (2) the fighter is able to use their reaction, and (3) the fighter has at least one Superiority Die available.

In terms of narrative, the fighter could have used their shield to parry the enemy's attack.

If a Battle Master maneuver requires a weapon (or shield), then the maneuver text will specifically mention it. For example, the Lunging Attack maneuver says:

When you make a melee weapon attack on your turn...

Answer 2

A Battle Master needs no armaments to Parry

Nothing about Battle Master, Maneuvers, nor Parry require the Battle Master to be armed. Furthermore, 'parry' is often defined from fencing (the definition you used) where it is assumed that opponents are dueling with equal arms; however, the dictionary definition makes no requirements that a person use something specific to in a parry.

1. to ward off a weapon or blow
2. to evade or turn aside something

They don't even need a shield; they could do this with the flat of their hand/gauntlet/etc.