The Anime Lad
A man is reborn in another world as a sentient sword. This provides excellent weaponry and no hands. He meets Fran, a desperate girl trying to escape people who intend to sell her. She needs a weapon. He needs someone capable of carrying one. The partnership begins under unusually clear practical terms.
Super Eyepatch Fox
Reincarnation produces a sentient sword instead of a warrior. Fran encounters him while fleeing captivity. His power can help her fight, and her grip gives him a way to move through the world. Weapon and wielder become an unconventional master-student pair, each supplying what the other lacks.
Gigguku
A talking sword lands in Fran's hands at the exact moment she needs power. That is an immediate partnership, not a decorative gimmick. He can guide and protect. She decides where they go and puts the blade to use. The premise turns one bizarre reincarnation into a two-person adventure, and I am ready to cheer for both halves!
Father's Basement
Reincarnating someone as an object can feel like a novelty stretched over standard fantasy. Making that object a weapon at least creates dependence. Fran is fleeing a brutal situation and needs strength. The sword needs a wielder. Their arrangement gives the power fantasy two participants, which is more promising than letting one overpowered traveler collect abilities alone.