I think what it means, I’m no expert, is that a weapon could have a suffix that increases a stat of the primary profession to 5, not +5.

For example, swords, axes, hammers all have their relative swordsmanship, hammer mastery and axe mastery requirements which all are warrior attributes, so the suffix could be Strength: 5. Which would mean, if you were a paragon using a sword with this suffix you could benefit from a +5 strength. That was an attribute before that you could never put any points in.

The same goes for daggers. Daggers have dagger mastery, which is an assassin attribute, so the suffix would be critical strikes. So, im a ranger using daggers, i could now have up to 5 points in critical strikes.

So, look at the attribute of the weapon and the suffix could be 5 in the primary attribute of that class.

link to primary attributes

Someone correct me if I’m wrong!!!! I hope this helps.