I think the intent was for Brawler to affect bare hand attacks
<item name="meleeHandPlayer"> <!-- T1 brawling -->
<property name="Extends" value="meleeHandMaster"/>
<property name="Tags" value="blunt,melee,grunting,light,perkFlurryOfBlows,attFortitude,perkBrawler"/>
<property name="CreativeMode" value="None"/>
<property name="HoldType" value="0"/>
.....
<effect_group name="meleeHandPlayer" tiered="false">
<passive_effect name="EntityDamage" operation="base_set" value="5"/>
<passive_effect name="BlockDamage" operation="base_set" value="2.2"/>
<passive_effect name="DamageModifier" operation="perc_add" value="-.5" tags="earth"/>
<passive_effect name="DamageModifier" operation="perc_add" value="-.5" tags="stone"/>
<passive_effect name="DamageModifier" operation="perc_add" value="-.5" tags="metal"/>
<passive_effect name="AttacksPerMinute" operation="base_set" value="80"/>
<passive_effect name="StaminaLoss" operation="base_set" value="10.5" tags="primary"/>
<passive_effect name="MaxRange" operation="base_set" value="2.0"/>
<passive_effect name="BlockRange" operation="base_set" value="2.6"/>
</effect_group>
<effect_group name="Power Attack" tiered="false">
<passive_effect name="EntityDamage" operation="perc_add" value="1" tags="secondary"/>
<passive_effect name="BlockDamage" operation="perc_add" value="1" tags="secondary"/>
<passive_effect name="AttacksPerMinute" operation="perc_add" value="-.3" tags="secondary"/>
<passive_effect name="StaminaLoss" operation="base_set" value="15.8" tags="secondary"/>
</effect_group>
<!--use_action class="LiftUpTerrain" delay="1" use_time="..." gain_health="-5"gain_stamina="-20" gain_food="0" gain_water="10" gain_sickness="15" condition_raycast_block="77,78,79,80" sound_start="player_drinking" /-->
</item>
They have the tags for it at the top, but don't tie the damage to the perk (missing tags at EntityDamage). Not sure if that was just missed or if they were having issues and removed it. They also don't have the tier bonus damage passive effect in there.