thanks for the feedback :) and yeah i just did realize the item bit. i think the Dancer's good though, you do use all of it's ups, especially the atk spd for the passive

First of all hello :)

Here is some feedback and criticism.

Summoners Spell are up to preference, but Pantheon defenetly needs Flash for immidiate escapes and for awesome combos with Aegis of Zeonia.
Ghost may be useful for chasing people around, but can be easely shut down from slows and stuns.

Your runes are fune, although I would reccomend Greater Glyph of Scaling Magic Resist instead of Warding.

Starting with 3x Mana Potion in lane is a bad idea because you won't have any kind of sustain against enemy harassment. If you want mana regen its preferable to swap up your runes a bit. Heal should be used to bait people inside fights and give you an advantage in sticky situations, not for staying in lane.

Throw Phantom Dancer to the trash can. It a very bad item for Pantheon. You don't need the bonuses it offers, and it consts almost 3k gold. Replace it with an item for damage or survive ability instead so you won't melt inside fights.

Double Infinity Edge is a bad idea for any champion. Its super expensive and the passives don't stack. Change on of them for an item for lifesteal and damage of for more survive ability, because Frozen Mallet is not enough when focused fired inside the fight.
In general your items need a lot of work. And they defenetly don't work on 30 lvl.

You need to extend your gameplay section, instead of just discribing the basic combo.

You can improve your guide greatly by reading the guide about making a guide, which can be found here. It helped me greatly assembling my guide, and I hope it will be useful for you as well :)

Anyway this is my feedback, criticism. Hope I helped :)

Hl & Hf!