Just a few ideas for making spotting more interesting and giving the rangefinder a bit of use.
Rangefinder:
-Allow it to spot ships
-Remove the alleged targeting aid
-Allow it to measure range when un-zoomed
-Display range below spotting box
-Possibly add (relative?) velocity and altitude measurments when zoomed, probably only for the user to avoid having 4+ lines of text below the spotted ship
Spyglass:
-Needs a small ability to match that of the rangefinder, the ability to reveal some other aspects of the target ship would make sense.
-Hull damage - the minimum would be displaying a name for each of the already visible damage states (Minor damage Severe damage etc), more accuracy might an option or might be too much.
-Component damage - seeing armor damage might be a bit op, particularly for flak/mortar users but it could work.
-Gun state - take a bit of time out of your busy engineering schedule to tell the captain how close the next hwacha barrage is or what kind of ammo they have loaded into thier carronade.
-Maybe allow it to spot through slighly more cloud cover than the rangefinder
Listening Device:
Amplifies game noise (engines and guns basically) in the direction its pointed in while supressing noise outside that direction (probably include game music but exclude chat).
-Hopefully would reduce hide and seek a little bit in a reasonably fun way
-Would make both ambushers and targets easier to detect, hopefully balancing out