1) Magic can make things do all sorts of stuff. Including making ice, bone, or even light into a weapon that is very effective.
2) Accident. Alaznist's ranseur has a different Runelord of Wrath's skull on it, not the first. ALTHOUGH... liches rebuild their bodies once killed, so perhaps she killed him at one point and took his skull and let him rebuild!
On #2, considering by Alaznist's reign Alderpash would have been very (un)comfortably tucked away in the Abyss for at least a couple hundred years by Baphomet, I highly doubt Alaznist would have taken a field trip to the Abyss just to get a neato trophy for the butt end of her ranseur. :P
On #7, I meant the fact that by RAW you can't make a scythe out of bone, since you can't make a two-handed slashing weapon out of bone. Although I guess if you jerry-rig a wood handle and a bone blade like Krune's dragon-tooth longspear, you can get around that. I'll just chalk it up to "10,000-year-old wizards did it." ;)
Two new questions!
1. How was there an art mix-up for Sorshen's guisarme, considering it's never been depicted in official art?
2. Alaznist has been called an arcane knight before. Was that just for her enjoyment of using evocation, or did she actually wear armor? (You've mentioned before that she would not have levels in Eldritch Knight.)