I'm confused about the criteria Aizen was using in regards to their strength. Ulquiorra seemed much stronger then all the others as did Barragan. The supposedly strongest one Yammy just had size and strength going for him and after returning to the Soul Society Kenpachi remarked that the fight was 'Boring.'

How would she react if she accidentally killed his gigai?
I've always pictured him starting fights while in his gigai as a handicap/test and when it is 'killed' he is standing next to it looking down at it in irritation before saying 'You killed my Gigai.'
Also Zanpakto need release phrases not just names. May I suggest 'Waves rise up and crash down'? Though if I remember right those who've achieved Bankai don't require to sa the release phrase all the time.