Hiya,
Very late to this - in general there seems to be a theory that each Shard is associated with a number. Thus far we seem to have Preservation (16 - number of metals used by Allomancers), Ruin (theorised to be 11 - number of spikes in an Inquisitor), Endowment (assumed to be 5, per someone else's reply), Honor (10 - orders of Radiants, etc), Odium (may be an Oathbringer spoiler).
This may be related to the original sundering of Adonalsium, but is a bit unclear.