Re: Weapons training leads to good aikido.
Shodokan introduces weapons in the second and third dan. The second dan kata are based on knife attacks and third dan goes with jo and bokken in both tori and uke's hands with the addition of the tachi waza (bokken vs bokken).
Jo work (mainly the 6 and 18 jo kata) are included and should be practices from time to time even if I do not think that they are part of the syllabus.
Our basic hand and foot movements are based on sword strikes and whenever I teach them, I always use a bokken to demonstrate where the moves come from.
On a side note, many Aikidoka do not know how to use a real sword at all even if they have trained in aiki-ken or whatever. Using a sword is an art in and of itself. There were several past threads on the subject, just search for it.