Does this need a bit of hard limit on maximums?.
If not, adding stats of 7 to a model means they can not fail a roll using that stat.
For example if a model has an activation and defense of 7 it is a practically indestructible.
On the other hand that model, with no other "bits" on them costs 10 points, so maybe a mob of cheap fast things might be able to get the relics first, but it starts to make the abilities less meaningful and becomes a stat race.
I don't know, perhaps just a single line saying a model can't have more than 2 stats over 5 (seeing as move already starts at 6).