Hello,
new Artweaver is out (0.4.4)!!!
http://www.artweaver.de/index.php?en_version
There is also brand new pluggin for blending textures:
http://www.artweaver.de/forum/viewtopic.php?t=527
http://www.artweaver.de/direct/BlendIf.zip
With this plug-in you are able to do this magic like in Photoshop
http://www.cgtextures.com/tutorials/blendif/tut_blendif.html