I never heard that "wabi" acronym :) I like it!
Wabi is a japanese aesthetic concept , properly "wabi-sabi" that refers to wear and impermanence. From the Wikipedia entry:
"...the student of wabi sabi learns to find the most simple objects interesting, fascinating and beautiful. Fading autumn leaves would be an example. Wabi sabi can change our perception of our world to the extent that a chip or crack in a vase makes it more interesting and give the object greater meditative value. Similarly materials that age such as bare wood, paper and fabric become more interesting as they exhibit changes that can be observed over time."

Sounds like "patina" to me.....LouS