What is the awakening limit for generic 1* summons?
Solution 1:
Not all units are upgradable to "full" 6 Stars. For the most part, 1 Star units won't exceed 3 Stars, once fully Awakened.
You can see a full list of Units, as well as their max Star Rating here. This list groups units by their Max Star rating, then lists their base Star rating next to each individual unit.