BlendTree cause sword out of scabbard

Two animations, one is idle, another is run.
When playing these 2 animations alone, everything looks fine.


But after blending these 2 animations in a blendtree, strange things happen


Sword will out of scabbard during transition.


Is there any way to fix this?

Project:http://www.mediafire.com/file/xn13ew2nyrrdz81/AnimatorBlendProblem.rar/file

Thanks in advance!