Some disclaimers before i get into it:
-Yes, I have searched the forums for this specific idea and while some suggestion topics may be similar regarding the original subject there is no suggestion as specific as what I am about to propose.
-I do acknowledge that Spiral Knights is not a 'dress-up game.'
So rather than the anti-climactic icon change, how about we bring something we can really show off? By the time anyone breaks that 45k prestige milestone, they have no doubt proven they are a seasoned Recon Ranger. Why not give us a set of gear to prove it? A Helmet and piece of Armor in the style of our choosing with the recon ranger colors & markings. This can be a costume piece, as we most likely have a set gear loadout that suits us best for each danger mission.
While the Armor & Helmet would be nice, Let's make it a complete set by also throwing in a shield. How about a solid Normal, Elemental and Shadow defense one? Sure this may look like Darkfang Envy, but of course the standard balancing exercise that any piece of gear would have to undergo applies here to make sure it isn't too OP, but it should be something special as it takes time to break that 45k mark.
So here's the one criticism I can think of: What if someone gained 45k prestige by only doing the "monstrous research," "supply delivery," "Arms Appropriation," and "geological survey" missions? Well ok you got me there, I am not entirely sure how to reconcile these. My only thought is to weave in a mechanic in the game that tallies the points more specifically. Say it gives you the total number of prestige points, then when you hover over the number it breaks it down in how many points in Danger Missions, Daily Prestige, and the other soft prestige missions? Just a thought.
Much if this is open ended & free for amendment. Feel free to comment, thanks!
Honestly, I know there are some ... let's call them "strange", people on the forum, but you can't take anyone seriously who thinks that's an argument. Let's say you get around 100 Prestige on average when completing one of the three (100 being generous here), it would still take 450 days to get 45000 Prestige. Anyone who went through that totally deserves whatever reward there is for so much Prestige.
To have pointed it out, someone who actually does the "Arms Appropiation" probably deserves to be banned for a week or two, as he must have far to much time on his hands. Not to offend anyone who does it, but honestly, who's willing to do that?
Except for that: Prestige exclusive content, like gates or whatever would be nicer, but I guess a costume would be a start. It's not much, but hey, they can build from there.