public IPathIconSelector PathIconSelector { get; set; }

Public Property PathIconSelector As IPathIconSelector

<Window.Resources>
    <local:IconSelector x:Key="iconSelector"/>
</Window.Resources>

<!-- ... -->

<dxe:BrowsePathEdit DialogType="Folder" PathIconSelector="{StaticResource iconSelector}">

using DevExpress.Xpf.Editors;
using System.IO;
using System.Windows.Media;
using System.Windows.Media.Imaging;
// ...

public class IconSelector : IPathIconSelector {
    public ImageSource Select(string path) {
        if (Directory.Exists(path))
            return new BitmapImage(new System.Uri("pack://application:,,,/Open_16x16.png"));
        return null;
    }
}

Imports DevExpress.Xpf.Editors
Imports System.IO
Imports System.Windows.Media
Imports System.Windows.Media.Imaging
' ...

Public Class IconSelector
    Inherits IPathIconSelector

    Public Function [Select](ByVal path As String) As ImageSource
        If Directory.Exists(path) Then Return New BitmapImage(New System.Uri("pack://application:,,,/Open_16x16.png"))
        Return Nothing
    End Function
End Class