Skyrim:Bound Weapon

Bound Weapon causes the spellcaster to be equipped with a magical version of the specified weapon for a duration of time, after which the weapon vanishes.  To dispel the weapon before the time has elapsed, sheathe the weapon, or simply equip another spell or weapon in that hand.

Types of Bound Weapon
In each case, the second (Mystic) version of the weapon is the one that appears if the Mystic Binding perk has been unlocked.


Notes
Bound weapons cannot be disarmed.
If the Soul Stealer perk has been unlocked, bound weapons automatically cast Soul Trap on strike.
If the Oblivion Binding perk has been unlocked, bound weapons automatically cast Banish and Turn Undead on strike. Both effects are level 99, so they will affect any susceptible monster. 
Equipping a weapon or spell while using a bound weapon will cause the bound weapon to vanish.
The exceptions to this are the Bound Sword and Bound Dagger .  It is possible to equip another one-handed weapon or spell in the other hand.  Note which hand the weapon appears in so you can choose the correct one.  When cast normally, the weapon will appear in whichever hand you cast the spell from.  If dual-cast, the weapon will appear in your left hand, so you can afterwards equip something else in your right.  You can even dual-wield two Bound Swords/Daggers by casting them separately.
You can also use a shield along with the one-handed bound weapons, but only in your left hand, so the weapon must be cast with the right hand, and thus cannot be dual-cast, since dual-cast always equips the weapon in the left hand.
It is not possible to use any kind of Bound Weapon while on horseback.  Mounting a horse automatically sheathes your weapon first, cancelling the spell.  And you can't cast spells while mounted.
Conjured weapons can be poisoned.
Conjuring a weapon makes noise, which can attract unwanted attention while you are sneaking. This can be prevented with the Quiet Casting perk.
Using bound weapons in combat also increases your Conjuration skill, on top of the skill associated with the bound weapon used (One-handed for the Bound Sword and Bound Dagger , Two-handed for the Bound Battleaxe and Archery for the Bound Bow).  No Conjuration experience is gained by casting a Bound Weapon spell out of combat; however, if you cast a conjuration spell before combat, and later enter combat with the conjuration effect still in place, some Conjuration experience is awarded.
Bound Bow will also give you a quiver of 100 Bound Arrows upon casting, which acts as any other bound weapon. Bound Arrows have a damage rating of 24, the same as Daedric Arrows.
The Arcane Archer Pack  adds an adept conjuration spell tome to the game, Bound Quiver, which gives you a lesser power to summon 100 Bound Arrows separately (so it can be cast while you wield a bow to prevent the need to recast Bound Bow). Unlike the Bound Arrows from Bound Bow, these arrows are affected by Mystic Binding, granting them a damage rating of 32 (considerably higher than the previously most powerful arrow, the Dragonbone Arrow with 25 damage). So to maximize damage with Bound Bow, you need to cast Bound Quiver after casting Bound Bow, a combined base damage rating of 56.
You can use the arrows of your choice along with the Bound Bow (e.g. Dragonbone Arrows, which are the only ones that are better than Bound/Daedric Arrows), by equipping the arrows after casting the spell, though you can't get your Bound Arrows back without recasting the spell.  Regular arrows will still deplete as normal if you use them with a Bound Bow.  You cannot, however, use the Bound Arrows from the Bound Bow Spell along with a regular bow (as unequipping the Bound Bow will also make the quiver vanish).
The Arcane Archer Pack's Bound Quiver provides the ability to use Bound Arrows with a regular bow.
Any Bound Arrows that you have fired (whether they hit or missed) will continue to exist in the world even after the spell expires until you leave the area.  They cannot be picked up or found in corpses' inventories like other arrows.  As they are very easy to see, they can be useful as markers to remind yourself where you've been. The arrows can contribute to bloating a save game.
The Bound Bow is an exceptionally desirable weapon in the early stages of the game - unmodified through perks, it is very fast and of Daedric power. The relevant Spell Tome is found in Fort Amol Prison under a lantern in a bucket, guarded by five mages in total. Casting the spell will require 183 magicka at 15 (base) Conjuration skill, <180 as of 17. This amount of magicka may be achieved as early as level 1 via Necromancer Amulet (50 magicka bonus and + 25 fortify conjuration) or any combination of  Novice Hood (30 magicka), Atronach Standing Stone (50 magicka, found just to the east of Fort Amol) and Altmer Highborn racial bonus (50 magicka) as well as outright through periodic consumption of Elsweyr Fondue (100 magicka).
With Patch 1.9 the Bound Bow with Mystic Binding garners more XP per hit than any other bow in the game.

Bugs
  
The issue appears to only arise when you cast in the third person view, so as long as you remember to switch to first person before casting you shouldn't have any problems.
Sitting down will fix this.
Equipping a one handed weapon will fix this.
The invisible bound axe can be "unequipped" by equipping hotkeyed spells.
 
 
 
 
 

See Also
Weapons &mdash; A list of all weapons available in Skyrim and their damage.