It's not a "trouble" thing caused by a weird arrow shaped thingy.
The Signal Offset is just that - it offsets the next signal ahead, essentially a mirror. I've found two uses for it, one is the advertised use by NS37, the other is one that I think he's said it's not really meant for... Both of which are intended to make for prototypical looks while appeasing the Trainz AI.
Say you have some smaller yard tracks which do not have dwarf signals at the ends in real life but you need to have it in order to keep your AI from complaining about unsignalled track (or you want them to wait at the end of the yard track until all switches have been aligned for them to reach the end of the crossovers), you place Offsets at each one - it will act as a red signal if it does not see a signal ahead of it to copy, once it does it will copy that signal. The reason for this is that AI would set a turnout or 2 ahead, travel a little bit, set the next, etc... If it got to a switch which was locked or whatever, it would sit in the middle of these crossovers/ladders and block all sorts of things while waiting for the switch to clear. Using the offset holds the train in its own track until there is a clear path to the signal and that signal was something other than Stop. I'm guessing this is what the offset was used for here, and likely what was happening was that the AI wasn't tryng to switch junctions far enough ahead to get the offset to clear the Stop... It might be annoying but it's closer to real life because if there was a locked junction ahead that wouldn't let it completely clear the siding or whatever it was sitting on, it will sit there instead of moving a little and then blocking other junctions because it's stuck.
I've been known to use it from time to time where a signal prototypically sits on the far side of a grade crossing and you want the train to stop and not block the crossing if the signal is red. In real life engineers know better than to do this and will stop their trains before the crossing. In Trainz AI, they will sit there and creep creep creep on the signal until they're so close they're practically under it... (annoying with signal bridges because they stop so unrealistically close that it bugs me but I ignore that one). The problem, and NS37 will probably tell you the same thing, is that it is typically seen as an extra "block" when calculating so sometimes you end up with unrealistic block signal indications.