Switchblade

You hold a non-magical dagger or club. When you cast this Spell, the weapon grows to resemble a much larger blade or bludgeon. The weapon now does d8 damage. The weapon retains its other properties, though if you use a dagger, you may choose to change its damage to Slashing rather than Piercing. The weapon is considered magical for overcoming resistances. The weapon returns to normal if it leaves your hand, you are knocked unconscious, or the spell ends.

At 5th level the weapon gains a +1 bonus to hit and damage, +2 at 11th level, and +3 at 17th level.