We’re using a lot of assumptions here and I think it is the safer assumption. Your goal is to avoid the new unlock mechanic for as many weapon families as possible. You are not alone but the design goal is to migrate blessings in such a way that players do not feel they have lost progress. Migrating four slab shield blessings to twelve blessings goes a bit beyond preserving progress.
Regarding the target you are aiming for in your spreadsheet. I would use the same weighting as you because it matches how item level is calculated atm. If you apply your weighting system to Strawhat’s comment then you only need to have learned 50% of the maximum points to achieve full mastery in that family. This forces a further assumption though: Either the actual points value per blessing varies wildly from family to family OR it is 50% of a typical blessing family.
For a conservative estimate I would recommend modelling using the expanded pools and setting a target per weapon family of 50% of the average max points for all weapon families. If you max out more than that on the day then you’re happy with the gift.
Edit: One of the dev intents is to normalise the number of blessings per family. That might influence some of the assumptions above.