An archmage's staff would indeed be special other than the fact that it is used by an archmage. It is a living extention of that individual's power, and each staff is made personalized. Recieved as a mark of their rank, the staff can add a little kick if the mage has depleted his energy and with it, his natural powers can be amplied in the sense that the spells he casts with the staff would be stronger, more devestatiing or healing, etc, than if he was to do the same spell without its assistance. While the possibility of this item becoming a crutch, handicaping a mage, this is also rather useful, because the owner can put his or her own magic into it for later use.
Now, because this is a Warstaff, not a archmage's staff, this battery property has been taken out of the item and replaced with a stronger offensive side. We can leave that up to the actual user to decide how powerful he wants it to be. This could become a ledgendary weapon, as it has in my own RP world, or it could be a standard weapon among a certain cast of warriors or something like that.
Now, about the warhammer. I know that a warhammer is a specialized item in many RP worlds, but in my mind's eye, I'd call the hammer a double sided weapon, with spikes on the rim of either side, but a flat surface on each end for pounding or smashing or whatever violent act would be inflicted. When mounted on the staff, it could indeed become unwieldy. So you must remember that when using the hammer head the Warstaff is a two handed weapon or a one handed weapon for extremely large individuals, say on people larger than eight feet or something. As for weight, I could go the easy route and pass the weight off to some magic or something like that that would make it easy to hold and use. I won't. The Warstaff is heavy, I'd estimate around eighteen pounds minimum. In addition to that is its size, which is why this is a Battlemage's weapon and not an ordinary warrior's. Battlemage's are a unique class of warrior, mages with strong fighting abilities. Requirements for entrance to this cast is body structure at least six feet two inches, 160 pounds and excellent physical shape. No weak but powerfully magic mages here. As a result, the magic aspect of these warriors can be blunted, since they are first warriors, second mages. This weapon would then be a great help, as it has the archmage staff's ability to enhance a spell when it is casted with the aid of the staff but it is also a functional weapon, abet one that is rather large.
I hope that made any coherence sense... I just woke up. Go to Comment
"Yn these landes, theye do ryde upone greate flowtinge beastes alike as those thate ye fyshermen do calle nawtilus; Ande these beastes, callede 'pyky-pyky' because of ye noises thate the beastes make, are troubelsome ande beastlye mountes, withe fowle temperes." -Telliamed ap Ynris, "Ye Westerne Landes".
(A levitating giant nautilus that makes a noise like "piki-piki" and is thus called a Great Piki-piki.)