(All of them Generally proc at their High-Point. Rarely resist.)
And as per Spicyryan, I Agree... Things are generally assumed entirely too much. In the 'math' of Togekiss, There are too many assumptions and not enough facts. its Guess-work.
For instance, Triple Attack takes precedence over Double Attack, Stands to Reason Quad > Triple. Needs Testing.
That being said, This might be a more favorable off-hand for a 5/5+2 Empyrean THF, Not cause its a better dagger (its not), But because of the enhanced chance to proc +2 Set Bonus.
You are adding extra attacks. 3A is three swings, but one of those swings is natural and doesn't count. You may swing nine times during 3A procs, but only six of those are additional attacks.
@ Karbuncle
1) It's most likely 3%. SE likes to theme drops. Threes would be the theme of this dagger (it's named Triplus after all). Moreover it's a theme SE has used before (Algol). It's basically a 1.2% increase in damage in an optimal triple build. That's pretty significant for close parses.
2) TP drain is only 10%. You can math it down to be +1 TP to the expected normal TP return of the dagger. Moreover a lot of your pro-Twilight posts were back when you put it at a ridiculous 30% proc.
3) 3A damage + is gravy. This dagger is still a strong offhand due to the low overall delay and good dps. The match up between Twilight and Triplus as an offhand comes down to the TP drain vs. better dps and synergy.