[Lolzytripd]

1) should not be a 100% guarantee to knockdown, IE if your trip did no damage, no knockdown, or if you are strong enough you won't be blown back 100% of the time.
this gives Strength a use other than damage and carry weight, HELL you could tie it statistacly to bw max carry as your chance to resist.
2) once knocked down should cripple evade