When using jelkhor’s blast knife and frostfang arrow:
Suckerpunch arrow node in detonating arrow does not function properly in that if you hit an enemy that already has an arrow, it only increases damage and radius approximately 20% of the time. This is very apparent when attacking a lone enemy such as an elite or boss. In this case suckerpunch arrow almost never procs (maybe 2% of the time).
Rapid detonation also does not seem to work in that sometimes explosions happen immediately regardless of a second hit and sometimes even with a second hit there is not instant detonation.
To be perfectly clear, the interaction between suckerpunch arrow and rapid detonation DOES NOT work either. Larger damage explosions only happen about 3/10 times, and never happen on a solitary, large enemy.