I made a Vertical scrollbar with only repeat buttons and pls have look.
<LinearGradientBrush x:Key="VerticalScrollBarBackground" EndPoint="1,0" StartPoint="0,0">
<GradientStop Color="#E1E1E1" Offset="0"/>
<GradientStop Color="#EDEDED" Offset="0.20"/>
<GradientStop Color="#EDEDED" Offset="0.80"/>
<GradientStop Color="#E3E3E3" Offset="1"/>
</LinearGradientBrush>
<SolidColorBrush x:Key="ScrollBarDisabledBackground" Color="#F4F4F4"/>
<Style x:Key="ScrollBarButton" TargetType="{x:Type RepeatButton}">
<Setter Property="OverridesDefaultStyle" Value="true"/>
<Setter Property="Focusable" Value="false"/>
<Setter Property="IsTabStop" Value="false"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type RepeatButton}">
<Rectangle Fill="White" Stroke="Black"/>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style x:Key="RepeatButtonStyle3" TargetType="{x:Type RepeatButton}">
<Setter Property="OverridesDefaultStyle" Value="true"/>
<Setter Property="Focusable" Value="false"/>
<Setter Property="IsTabStop" Value="false"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type RepeatButton}">
<Grid>
<Rectangle Fill="#FF9A2323" Stroke="#FF9B6363" StrokeThickness="2" RadiusX="2" RadiusY="2"/>
<Path Fill="#FF9A2323" Stretch="Fill" Stroke="#FF9B6363" StrokeThickness="1" Margin="6.619,5.209,4.317,2.207" RenderTransformOrigin="0.5,0.5" Data="M0.41792299,0.01261113 L10.7483,1.9116925 -0.026186385,10.702906 z">
<Path.RenderTransform>
<TransformGroup>
<ScaleTransform/>
<SkewTransform/>
<RotateTransform Angle="38.198"/>
<TranslateTransform X="-0.74530940575247584" Y="-0.07455335808536212"/>
</TransformGroup>
</Path.RenderTransform>
</Path>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style x:Key="RepeatButtonStyle4" TargetType="{x:Type RepeatButton}">
<Setter Property="OverridesDefaultStyle" Value="true"/>
<Setter Property="Focusable" Value="false"/>
<Setter Property="IsTabStop" Value="false"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type RepeatButton}">
<Grid>
<Rectangle Fill="#FF9A2323" Stroke="#FF9B6363" StrokeThickness="2" RadiusX="2" RadiusY="2"/>
<Path Fill="#FF9A2323" Stretch="Fill" Stroke="#FF9B6363" StrokeThickness="1" Margin="6.119,2.209,4.817,5.207" Data="M0.41792299,0.01261113 L10.7483,1.9116925 -0.026186385,10.702906 z" RenderTransformOrigin="0.5,0.5">
<Path.RenderTransform>
<TransformGroup>
<ScaleTransform/>
<SkewTransform/>
<RotateTransform Angle="216.44"/>
<TranslateTransform X="-0.74530940575247584" Y="-0.07455335808536212"/>
</TransformGroup>
</Path.RenderTransform>
</Path>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style TargetType="{x:Type ScrollBar}">
<Setter Property="Background" Value="{StaticResource VerticalScrollBarBackground}"/>
<Setter Property="Stylus.IsPressAndHoldEnabled" Value="false"/>
<Setter Property="Stylus.IsFlicksEnabled" Value="false"/>
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}"/>
<Setter Property="Width" Value="{DynamicResource {x:Static SystemParameters.VerticalScrollBarWidthKey}}"/>
<Setter Property="MinWidth" Value="{DynamicResource {x:Static SystemParameters.VerticalScrollBarWidthKey}}"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ScrollBar}">
<Grid x:Name="Bg" SnapsToDevicePixels="true">
<Grid.RowDefinitions>
<RowDefinition MaxHeight="{DynamicResource {x:Static SystemParameters.VerticalScrollBarButtonHeightKey}}"/>
<RowDefinition Height="0.00001*"/>
<RowDefinition MaxHeight="{DynamicResource {x:Static SystemParameters.VerticalScrollBarButtonHeightKey}}"/>
</Grid.RowDefinitions>
<RepeatButton Style="{DynamicResource RepeatButtonStyle3}" IsEnabled="{TemplateBinding IsMouseOver}" Command="{x:Static ScrollBar.LineUpCommand}"/>
<Track x:Name="PART_Track" IsEnabled="{TemplateBinding IsMouseOver}" Grid.Row="1" IsDirectionReversed="true" Visibility="Visible">
</Track>
<RepeatButton Style="{DynamicResource RepeatButtonStyle4}" IsEnabled="{TemplateBinding IsMouseOver}" Grid.Row="2" Command="{x:Static ScrollBar.LineDownCommand}"/>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="IsEnabled" Value="false">
<Setter Property="Background" TargetName="Bg" Value="{StaticResource ScrollBarDisabledBackground}"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>