Yes. As a comparison, the Doppelganger Card has the following script "bonus bAspdRate,33;", and getequiprefinerycnt returns the number of upgrades, for a +10 weapon that would be 10. So it is as you said, if you have a +10 weapon, the script would just say "bonus bAspdRate,5;", i.e. it's roughly one sixth of a Doppelganger card.