Re: Weapons training leads to good aikido.
I think there are several factors in this issue that are sometimes run together:
1. Morihei Ueshiba's own training history in aikido. He seems to have gone though successive stages: of dabbling with weapons, to intensive training with weapons (especially in Iwama), to virtually no training with weapons (from the late 1950s). These succesive stages are sometimes isolated and used as evidence that aikido is, or is not, a weapon-based art, and/or needs, or does not need, training with weapons.
2. Morihei Ueshiba's own teaching methodology. I am not sure how far this went, beyond teaching as showing and then expecting his deshi to understand what he had shown. Thus, having them take ukemi and be his partners for such weapons exercises as are found in Budo (1938) were the ways he did this. I cite this manual, because it is the only book containing weapons training that has Morihei Ueshiba as author.
3. The methods used by Morihei Ueshiba's deshi themselves to understand what he taught. By all the accounts I have from talking to some of them, the deshi understood neither what he was saying, nor what he was doing and had to 'imaginatively reconstruct' this in their own training. Every single Japanese aikidoka of senior rank (6th dan and above) I have talked to admitted to having trained with weapons and many devised their own training systems.
The development of a training system is a way into understanding the internal architecture of aikido as a budo, but the two are not the same. Nevertheless, all three factors outlined above come into play when considering aikido as a training system and as a budo.
Best regards to all,