Looks like I'm late to this party, but I wanted to put my idea out there... and I think my take is sufficiently different so here goes...
Theme: Tempting hapless victims to their demise using taunts, pulls, and trickery
Class Mechanic: Songs
The mesmer's shatter skills will be replaced with pulsing abilities called "songs" which are similar to shouts. The number of pulses depends on how many illusions you spend (1-3). The effects are offensive-oriented. Some will deal damage, others will provide temporary group damage buffs.
New weapon: Warhorn
Going with the theme of auditory expression, the warhorn seems fitting. It will provide a long range pull and a long range taunt, useful for CC bars and bringing enemies close so you can beat them up.
New utilities: Traps
Going with the temptress theme, traps are a good choice for mesmer. They can provide nice burst damage as we've seen with dragonhunters and rangers. The idea is you plant your traps and lure enemies into them with your siren abilities.
Trade-off: no clones
Since Anet likes trade-offs and the community likes reducing visual clutter, I figured I'd do a 2-for-1. No clones! Instead you generate wisps which float around your body to indicate how many "shatter charges" or "song pulses" you have saved up. A potential benefit to this idea is that enemy players love to see a lonely mesmer with no clones. They will be thirsty to run up and attack you because they don't have to worry about getting tricked by illusions. This will lead them into a false sense of courage as they come charging into your traps. As for sustain/survival, the Siren can make use of pre-existing stealth abilities, as well as trapper runes. The siren will be a truly nasty duelist even with no clones to hide behind.
The general pros are damage, CC, and group effects similar to frost spirit or soulcleave summit. The drawback to this spec is you have relatively low mobility and you are more vulnerable to targeting. You are essentially using yourself as bait to tempt enemies into attacking you, which you then turn the tables on them with big damage.