Oh... wait. You were talking about your zanpakto. >.> Well, my suggestion was, as I've said before,
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If I may suggest something, I'd say give that ability to bankai, and in shikai, try to limit your power so that they don't seem too powerful. You could give your shikai an ability to turn the area that you hit with the weapons instead into quicksand/normal sand (not things). You could also control the sand, for example, and make a miniature sandstorm, etc.
Your bankai, on the other hand, seems to be nothing much changed except different appearances and longer chain. You could include the turning-things-into-sand ability here, but also add in a limiting reactant condition: maybe your reiatsu, maybe the size of the object, etc, so as not to make it too cheap. And maybe you can include a few techniques using sand in shikai/bankai... Like trapping the opponent using sand, sand blade, whatever.
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Or maybe you could ask ILPy.