You could get a heck of a load of bids, that's for sure. The only reasons I use Calibur over Brandish are:
1. I prefer normal damage to specialized.
2. The charge attack is awesome against things stuck in a corner, in a freeze haze, turrets etc - basically, anything that won't get knocked back by it. It's also better for crowds (since when do people charge for single enemies? Not me) than the Brandishes, this being, the knockback gives you time to charge it again, and you don't freeze/shock enemies who might just hit you straight afterwards.
My advice? Start on 10k, put the time on Very Long (2 days) but don't put on a buy now price, if you are selling it because you have a better weapon. If not, then KEEP IT! You will probably need at least one crowd-control sword in your arsenal.

@Haladin No you can't, Raisinfist just isn't really experienced with this kind of thing.

What you should do is:
1. Move this to the Bazaar.
2. After getting their advice, make a thread saying you WTS (Want To Sell) it. You can make the subject line witty or to the point, your choice.
3. In the OP of the new thread, set up a little forum auction for yourself. Make the staring bid, hmm, 5k seems good. And the buyout at the 20k you want (it's still high, but buyouts are meant to be a bit ridiculous). If you want you can set up a timer or something for it.
4. Take bids from posters until the time runs out, buyout is reached, or if you're happy with the offer you're getting.
5. You may want to bump the thread to keep it on the first page. Spam like that is allowed in the Bazaar.
6. Work out when and where to meet the winning bidder to do the trade.
7. ...
8. Profit!