I think you are trying to do too much with one feature, and are running into a underlying divide by zero issue at the tips. Select all your sections as direction 1 and you should get your blade, and then create the tips with other means. Although I would be tempted to build your blade past the tips and then trim it back.
Are you going to use Guide1 and Guide2 for guide curves? if so, you'd have a problem of self-intersection geometry
and As Matt suggested, you'd better break it into small sections; otherwise, its hard to use one feature for all
I looked at your sktches and have some splines problems, i think,
it is becoming over defined when i try convert and add more divisions points,
what matt sad its true.
my tips for you:
try rebuild your splines to something like that:
I remade it with two splines and you need to do all sktches with the same number off "divions/points" it is important to use loft or bondary surfaces
to better results remember to do the guide lines in "center of tangency out" i dont know how splain that
take a look (you can use 3D splines for that) for exeple:
when you goint to build a surface try use "selection manager" to select only top section and build only the haf surface:
after that make another side using the surfaces lines and add tangency contition
the ends lines I whould do something like that to avoid some futute problem with your surface (like shell tool)
I think this should be enough to fix your model.