I'd like to take a crack at this.
I don't agree that they should have spells, but I'd like to add some raw arcane power: let's key a lot of these abilities to Charisma, which strikes me as more akin to biotics anyway. Let's make charging central to the class, and give them lots of goodies when charging. Naturally they should be melee-based, as shotguns in Pathfinder don't work the same way they do in Mass Effect. I also want this class to feel very high risk/high reward, so it should play like a glass cannon that constantly needs to charge his opponents and knock them down.
D10, Full BAB. Good Fort, Poor Ref and Will, 2+Int skills per day.
Acrobatics (Dex), Craft (Int), Escape Artist (Dex), Intimidate (Cha), Knowledge (Dungeoneering) (Int), Knowledge (Planes) (Int), Profession (Wis), Use Magic Device (Cha)
A vanguard is proficient with all martial weapons and with light and medium armour.
1 Arcane Strike
2 Kinetic Charge
3 Mobility Training
4 Kinetic Boost
5 Aggressive Charge I
6 Bonus Feat
7 Mobility Training
8 Vital Strike
9 Aggressive Charge II
10 Bonus Feat
11 Mobility Training
12 Improved Vital Strike
13 Aggressive Charge III
14 Bonus Feat
15 Mobility Training
16 Greater Vital Strike
17 Aggressive Charge IV
18 Bonus Feat
19 Mobility Training
20 Ultimate Charge
Angled Charge: When the vanguard uses Kinetic charge, he may make one turn of less than 90 degrees during his movement.
Careful Charge: When the vanguard uses Kinetic charge, he can remove the bonus he gains to his attack rolls from charging to remove the penalty to AC.
Charge Wave: When the vanguard uses Kinetic charge, a wave of energy is released that damages all targets in a 10-foot radius. The damage is equal to half the melee damage done by the vanguard's charge. A Reflex save reduces this damage again by half, and the vanguard is always considered to have saved against this damage.
Elemental Charge: When the vanguard uses Kinetic Charge, he leaves a trail of energy that damages anyone that passes through for 1d6 damage (acid, cold, electricity or fire) for every two vanguard levels. The trail lasts a number of rounds equal to the vanguard's Charisma modifier. The type of energy is chosen when the vanguard uses his Kinetic Charge ability, but can be changed freely each time it is used.
Flying Charge: When the vanguard uses Kinetic Charge, the energy he channels makes running unnecessary. The vanguard gains the ability to charge through difficult terrain or over gaps. The vanguard can charge foes in the air with this ability, but if he cannot fly, he falls immediately after making his attack.
Frightening Charge: When the vanguard uses Kinetic Charge, his target is frightened for 1d4 rounds. A Will save reduces this to shaken for 1 round. All opponents within 10 feet of the target must make a Will save or be shaken for 1d4 rounds.
Knockback Charge: If the vanguard hits his opponent while using Kinetic Charge, he can make a bull rush against that opponent as a free action.
Knockdown Charge: If the vanguard hits his opponent while using Kinetic Charge, he can make a trip attack against that opponent as a free action.
Sonic Charge: When the vanguard uses Kinetic Charge, his weapon is charged with sonic energy that does 1d6 damage for every two vanguard levels he possesses. All creatures within five feet of the vanguard (other than the vanguard) must make a Fortitude save or be deafened for 1 minute.
Versatile Charge: When the vanguard makes a charge attack without using Kinetic Charge, he can make use of one Mobility Training ability. For example, a vanguard with Elemental Charge and Versatile Charge could leave a trail of energy for any charge attack he makes. The vanguard can take this ability more than once; each time he chooses a different Mobility Training to apply to his Versatile Charge.
Thoughts? I haven't actually run any numbers, but hopefully it's not too weak or too strong. I like the idea of an arcane warrior, but I don't see the vanguard as buffing up or tossing spells.