Well, I promised some more...
TRICK ARROWS: Part 2
Multiple times throughout the series we've seen Oliver using injection arrows. A term, I believe, not uttered until the Season 2 finale. The first is seen in 119. Oliver uses it to counteract Vertigo.
In 218, Sara fills them with Tibetan Pit Viper venom.
In 219, Rampage Roy get stuck with a few.
These are used frequently in Season 2 (I'll update this post with more episodes soon). The collar looks to be essentially the same as the previous trick collar, just slightly shortened with internal features to show the fluid.
Not too long ago, the propmaster showed the following picture on his facebook page.
He referred to it as a "Taser Arrow", even though there already is a taser arrow (and these aren't really arrows anyway). Either way, these are what was fired at Slade from the "Counter-Measures Pods" (as the propmaster called them) on the Kestrel in 219.
Which finally leads me to...
We finally have a name for these add-ons to the bow. Confirmed to be made from scratch. The props used to actually open up and digitally fire the tasers appear to have a more blunt profile than what we've seen on the bow the rest of the season, probably due to the size of the pods vs the taser. Not much more to say than that.