For the siege weapon question of the week, have you ever considered turning the actual characters themselves into living, breathing siege weapons? Like you could essentially turn it into a skill tree item. Just as the classes already have their normal abilities, individual characters could have a "siege ability" associated with their specific class. For example, a sorcerer could be engulfed in his/her own magic and be transformed into a huge, energy being capable of significantly damaging a keeps walls and other players (With a range of new siege abilities). A night blade character could slip into the shadows and end up inside the keep walls, along with having a similar set of supe'd up, cool darkness abilities to attack those inside, but for a limited time. The dragon knight be transformed into an ethereal dragon and have a set of cool dragon like abilities; assaulting a keep in a ranged form. Then lastly, the Templar could become a God-like character, engulfed in light, and full of awesome light abilities to assault ground troops and heal friends. All of these abilities could be set to a timer or some sort of attribute atrophy, and only be available to the highest level of player, with a quest line of course. Also you could add more massive keeps, with multiple defense lines and walls, to be able to support a large amount of "mega-characters" who are assaulting a massive keep. Also to keep this stream of consciousness going, the Aedra and Daedra could give similar "siege trees" to give individuals a wider range of siege possibilities and quest lines. Provided that Zenimax makes sure that only so many people can use siege abilities at one time or makes use of a similar "finesse" bar for siege abilities. Personally I think it would be raw to have a PvP "God War" pitting all sorts of different siege abilities against each other.

Its Elder Scrolls, not Power Rangers

Sorcerers dont turn into huge beings, they summon atronachs for that. Peep dont just turn god avatars (except Martin Septim), they build Numidium for that.