[Psionic Powers] Vision-Based, Weaker Variant

[Shimmin Beg]

I'm looking at building some sensory abilities, and I noticed that Psionic Powers, p. 33 has Electric Vision with the "Vision-Based, Weaker Variant, -10%" modifier.

So far I've not been able to track this modifier to a source (but it might be an original here). I'm just trying to work out what this represents compared with the general Sense-Based, Reversed, -20%.

One possibility that occurred to me was a lower limitation value because this isn't an attack. It seems like a really useful modifier for Detect so I'd like to know the intention behind it.