You must read the Error patiently it points you to an Error.
Exact line of the Error pointing to the line in Hier.him 591 in that case.
You see a Mesh called.
Material is .mat File
exhst1_D0 is the Mesh that throws an error, open that with Texteditor go to Materials Tab
There's a list of Names to .mat Files
Check those Files for the header of tfMotionBlur command is added or not.
If it's added, remove that line. See what happens.
Removing it should stop Sknil from complaining,
but such edits are not to be done in a Game you intend to play.
It's just for visualizing, skinning purposes.
For Gameplay, you need to reapply such stuff.
You took an advanced Jet with a strange Mesh integration to work up.
At such builds, old Frankens, you will get into such issues.
Or at Hier.hims with custom edited Typos, a useless tab space left,
sometimes a weird numbering.
Depending on the Him fixing it can take one edit, or the whole Hier.him until
Sknil is reluctant to open.
Remember Sknil is very bitchy about such stuff. There's no room for marginal scripting error.
Hope this helps