It's worth noting that the fTP multiplier on these extra hits, much like most other multi-hit WS (Merit WSes being the main exception), will always have a value of 1, and will always return exactly 1 TP. By comparison, Onslaught's initial hit has a 2.75 fTP multiplier. A successful DA proc single-wielding therefore improves your WS damage by 36%, a successful TA proc by 72%, and a successful QA proc by 108%.