Originally posted by DarkSaint85

I was hoping you'd weigh in, nwg.
Strangely, maybe it's the side effect of the P5 force? I know everyone else (Cyke/Frost) had their powers screwy after it. But agreed, it might be writer error. For example, sometimes her Soul sword doesn't work on 'real' things:
http://i.imgur.com/KowZ0GT.jpg
Yet, does:
http://i.imgur.com/5PwQjWO.jpg
The Soul Sword started out as not being able to affect non magical beings and items but as she grew more powerful, she started affecting anything and everything in its path.
She turns a robot into a demon
http://static5.comicvine.com/uploads/original/10/108342/4909946-screen+shot+2015-11-15+at+11.38.15+pm.png
Affects non magical monsters
http://static2.comicvine.com/uploads/original/10/108342/5162690-screen+shot+2016-04-11+at+7.57.51+pm.png
Affects intangible beings
http://static2.comicvine.com/uploads/original/10/108342/3055309-83002982.jpg
Affects shadows (non-magical)
http://static9.comicvine.com/uploads/original/10/108342/4885879-screen+shot+2015-11-01+at+3.37.49+pm.png
http://static8.comicvine.com/uploads/original/10/108342/4840504-screen+shot+2015-10-07+at+1.05.55+pm.png
Affects psychic entities
http://static6.comicvine.com/uploads/original/10/108342/3030414-nm4.jpg
it can make inanimate objects bleed
http://static6.comicvine.com/uploads/original/10/108342/4886960-screen+shot+2015-11-01+at+11.17.48+pm.png
carves up a sentinel
http://static4.comicvine.com/uploads/original/10/108342/5167495-screen+shot+2016-04-23+at+11.15.27+am.png
ESPECIALLY as his blade responds to his thoughts, and can change direction midair. Note, too, the demon actually plans on doing as you say - using Fate's own blade on Fate:
http://postimg.org/image/nths8i0b7/
http://postimg.org/image/gozyzgt1v/
Moreover, it always hits its target - even when Fate himself isn't aiming:
http://postimg.org/image/4csh88ftf/
Her armor and portal shields should be able to counter it. I guess it's an anti magic blade but her armor blocked her own anti magic sword (swung by a demon that can break adamantium) and acts similar to auto shields
http://static5.comicvine.com/uploads/original/10/108342/3055351-2356480-8143feff667b372ce0674f1450815d37.jpg
http://static7.comicvine.com/uploads/original/10/108342/5109850-screen+shot+2016-03-22+at+10.29.00+am.png
http://static6.comicvine.com/uploads/original/10/108342/5109852-screen+shot+2016-03-22+at+10.29.46+am.png
http://static1.comicvine.com/uploads/original/10/108342/5112011-screen+shot+2016-03-23+at+8.42.12+pm.png
After reading the context behind the whole Mordru deal, I guess Magik getting her hands on the knife is unlikely.
Still think her teleportation and time travel are the keys to victory though...Magik taught Pixie how to teleport through magic but pixie needs to voice out a spell before she can port.