Magidin: Dweomercraft Unbridled (digiman619)
Vestige Level: 3rd
Binding DC: 20
Legend: The stories speak the tale of dwarven sorcerer, his name now lost to the ages, but most now refer to as Magidin. He was wild of beard, and even wilder of magic. He was said to be blessed (and cursed) with a powerful amulet, that added strange, powerful and chaotic effects to his magic. The rumours tell of how as a mere neophyte adventurer, he and his allies bested a much feared blue dragon! He went on to bigger and greater exploits, until one day, during a fateful battle with a potent psionic being known only as The Adversary, and in a desperate attempt to turn the tide of the battle, the heroic dwarven arcanist flooded all of his magical energies into one epic surge of wild magic! No one alive can attest to exactly what happened, but amidst all the chaos and the magic, the lights, sounds, explosions and mists, both the dwarf and The Adversary (who was said to wield blades of pure mental energy) vanished from reality, never to be seen again.
Manifestation: A mystical amulet appears spinning in mid air, pulsing with eldritch light. The amulet slows it's spinning and comes to a halt, and the light around it coalesces into the form of a dwarf. The dwarf opens his mouth to speak, when out of nowhere the head of a gigantic blue dragon appears and swallows the dwarf whole. Suddenly the face of the dragon contorts in pain, as the dwarf bursts forth from it maw, now wielding a blade of pulsing energy.
Sign: Your left hand is swathed in crackling black motes of energy (if for some reason you do not have a left hand, the manifestation takes hold at some other extremity of your body). These motes are completely harmless, and do not provide any illumination.
Influence: Magidin is a being of energy and wild magic. He insists that if you have a power, spell or magic item that can be used with random variable effect, you take no effort to affect the randomness of the outcome. Additionally, he also demands that you never pass up a game of chance if you are offered the opportunity to join one.
Blade of the Mind: as a swift action, you can summon a blade made of magic force to your hand. If the blade is dropped (or disarmed) it immediately vanishes, but can be summoned again with another swift action. It functions as a short sword, and you are automatically proficient with this blade. Any feats or other abilities that would apply to a regular short sword (improved critical, weapon focus, weapon finesse etc) function with the blade. Being composed entirely of magical force, the blade is effectively weightless, and can strike incorporeal creatures with no miss chance. The blade gains a +1 enhancement bonus to hit and damage per four binder levels (minimum +1) up to +5 at 20th level.
Sorcerous Blood: you can invoke any of the following effects at will (these function as supernatural effect which mimic the cantrip in question; caster level equals binder level): Dancing Lights, Detect Magic, Ghost Sound, Mage Hand, Open/Close, Prestidigitation or Read Magic. If you invoke a new effect while a previous effect is still operating, the previous effect immediately ceases - you may only ever have one of these effects in operation at a time.
Magic Surge: you bring forth a random magical effect as if activating a Rod of Wonder (the binder is considered the "rod wielder" for any applicable effects). You may produce this effect once per day, per point of Charisma bonus. Once you use this effect, you cannot use it again for 5 rounds.
Dragon's Bane: any melee or ranged attack, or other damage dealing effect, deals an additional 2d6 damage against creatures of the dragon type. This only applies to hit point damage, and never adds to ability damage or other effects not defined as hit point damage. The damage is of the same type as the primary attack that delivers it (i.e. piercing damage with a short sword, fire damage with a fireball etc.).
Resist Electricity: you gain resistance to electricity 5 whenever Magidin is bound. This increases to 10 at binder level 9, 15 at binder level 13, and 20 binder level 17 or higher.
Magidin and feats:
The Bind Vestige can grant Magadin's Sorcerous Blood ability, while Improved Bind Vestige can grant his Resist Energy ability.
I hope this vestige is OK. Not sure if it's balanced right as a 3rd level vestige? I considered making Magic Surge an "all day" ability, but that seemed like it might be a little OP.
Also hope this vestige appeals to you, digiman69. I tried to incorporate both aspects of what you asked for in a vestige into one.