Listening to the podcast you guys bring up the "WoW" idea of Legendary weapons. But if you really think about it with mods and everthing the "WoW" system of Legendary weapons is the worst possible idea for the items (I am talking of the items themselves, not the quest.) I think the system that LotRO uses for their Legendary weapons would be a amazing system for SWTOR. Once you do the quest and gain the weapon you would then be able to level that weapon up and make it more powerfull based on a good system. If you do not know much about the system, Ten Ton Hammer has a great write up on it.
I'd assume that any legendary weapon in SWTOR would either have additional stats or effects present on the shell as opposed to the barrel / hilt or be unmodable like the legacy weapons. Having additional stats/effects on the shell sounds similar to LotRO's system and IMO would be preferable to an unmodable weapon.
Here's the thing, Bioware has gone to painstaking lengths to make nearly everything in the game fully customizable from a stat viewpoint. Everything is moddable, you can keep set bonuses now while using whatever shell you want to, and they're apparently itemizing every piece of gear in such a way as to force you to spend your excess of credits from the dailies they keep finding ways to pressure you into doing by ripping apart 30 pieces of gear to fill 10 slots properly. Otherwise tier sets wouldn't have twice the required accuracy and enough crit/alacrity rating to push you so far into diminishing returns that the items become downgrades over previous tiers.
From their history any legendary weapon is going to be fully moddable, and the legendary difference is most likely going to be included in either the shell or barrel/hilt. My best guess is that they'll want to keep the shell legendary to appease people that want their legendary items to look legendary, so it'll either have extra stats or some sort of proc attached to it.
The other option is to make a piece of equipment that is completely unmoddable like the legacy token gear. This would keep it from being a great advantage in PvP since the loss of expertise would balance or outweigh any gains. It would also give the item a defined lifecycle so it isn't a mandatory PvE item several tiers of content from now and they wouldn't have to balance every future encounter around several operation members having it.
What they're most likely not going to do is implement an entirely new system into the game to allow players to only change the color of the crystal. They'll be spending enough resources creating the item itself and the method of acquisition, and the number of players that will even bat an eyelash at being forced into one particular color isn't worth the time and money to redesign entire game systems.
I'm not trying to sound harsh, just injecting a little reality.
Should Bioware actually decide to invest the time and money to create a game system that allows players to change only the crystal color of otherwise unmoddable items before they invest it in infrastructure or fixing the myriad of bugs that plague the game at the moment then more power to them as they hang themselves from a business point of view.
Here's the thing, Bioware has gone to careful measures to create nearly everything in the experience absolutely personalized from a statistic perspective. Everything is moddable, you can keep set rewards now while using whatever invest you want to, and they're obviously detailing every device in such a way as to power you to invest your unwanted of attributes from the dailies they keep discovering ways to stress you into doing by pulling apart 30 tools to complete 10 spots effectively. Otherwise level places wouldn't have twice the needed precision and enough crit/alacrity ranking to power you so far into reducing profits that the products become downgrades over past levels.at http://www.fifacoins2buy.com/
From their record any famous tool is going to be absolutely moddable, and the famous distinction is most likely going to be involved in either the invest or barrel/hilt. My best think is that they'll want to keep the invest famous to http://www.mmo2buy.com/RS2007-Gold.html please people that want their famous products to look famous, so it'll either have additional statistics or some kind of proc connected to it.
The other choice is to create a device that is absolutely unmoddable like the heritage symbol devices. This would keep it from being a benefits in PvP since the lack of skills would stability or over-shadow any benefits. It would also give the product a described lifecycle so it isn't a compulsory PvE product several levels of material from now and they wouldn't have to http://www.solorsgold.com/gold stability every upcoming experience around several function associates having it.