Since Michael is the dragon-slayer (destined to fight Lucifer/The Great Red Dragon during the Apocalypse), the astral dress could be dragon themed.

While Michael can't be a sword (Sandalphon) or a Spear/Lance (Raphael: "El Re'em"), maybe a banner (or cross) standard. I recon that it could probably act as a lightning rod, which would use electricity as an elemental attack.

For her element two big possibilities remain, Earth and Thunder.

Also, the Spirits do not have a bare handed combat specialist yet:

Tohka - Swordswoman

Yoshino - Familiar Summoner

Kurumi - Gunman

Kotori - Berserker

Kaguya Yamai & Yuzuru Yamai - Teamwork

Miku - Support

Natsumi - Variable (depents on what Angel she copies)

Origami - Long Range Fire

Nia - Intelligence Gathering

Spirit No. 6 - Bare Handed Fighter

the only i can think now about sixth spiirit ability is able to copy other spirits ability or combining angels, well i always dreamed tohka's and kotori's angel combined

that aside, looking at the sephiroth tree, 6 is the center of tthe tree and connected to all numbers. but of course that doesn't mean it will be like that

We got the title now...and there is the word Planet in the title. Maybe earth style powers. Though I wonder what her codename is going to be. Maybe something like Ghost to show a connection with Phantom,

A connection maybe, but unconfirmed. As for Phantom, I believe she and the Sixth Spirit are likely seperate individuals, and although Phantom is listed as a Spirit herself, I'm not convinced that she's like the others. She may turn out to be Spirit like in nature, but wholly different from the others on some fundamental level. The Bible does mention different types of Heavenly beings within the hierarchy of Heavenly Hosts.

We know what the sixth Spirit's name is going to be now (六喰). But the english translation for the name still seems to be in the works. Still, if it is pronounced like. Still if her name is pronounced like Ryukku, (リュック), then I'm going with Rikku for the name. Though I guess we will have to wait for the Hiragana for a precise answer.

BTW How many of you read the Light Novel in Japanese??

And how many of you wait for English translations? ( DO mention where you get them...)

精霊たちとの初詣、新学期の始まり。訪れた平穏な日常は宇宙からの隕石によって壊された。宇宙に漂う精霊、 星宮六喰の手によって。『むくは寂しさというものを感じぬのじゃ』地球からの想いは六喰に届く のか――

-so maybe Muku's angel is an invader gun and her codename is alien or U.M.A