New WS effect Info here

[Arcon]

SE takes the alpha value, which is .85 at 99, into account when reporting the value as 17%.

To be really brief, 17% and 20% are both accurate. 85% and 100% are both accurate. It just depends on far you go into the damage equation before pulling out the number.

This. The WSC is composed of the modifier (attribute bonus percentage) multiplied by the alpha value. 0.85*100% STR = 85% STR with 5/5 merits, for example.