I was missing the correct relative source. Using Self worked like a charm

<Button
    Command="{Binding CommandEdit}"
    Content="Edit"
    Style="{StaticResource DefaultButton}" />

<Style x:Key="DefaultButton" TargetType="Button" BasedOn="{StaticResource=DefaultButtonStyle}">
    <Style.Triggers>
        <DataTrigger Binding="{Binding Command.Hidden, RelativeSource={RelativeSource Self}}" Value="True">
            <Setter Property="Visibility" Value="Collapsed" />
        </DataTrigger >
    </Style.Triggers>
 </Style>