A unit of 4 Fanatic Brother knights is 1476 points (that is about as expensive as things come!). About the same cost as 63 poor skirmishing javelin! Assuming the javelinmen shoot on whites once, and are then run down - that would be 21 white dice with a 1 in 3 chance of wounding a knight. In theory the javelinmen should get 7 wounds...

Clearly a killer troop type!...