Anything you can lay your hands on can be permanently strengthened by you by imbuing them with your spirit. You will also gain a refilling pool of spiritual energy to enchant your objects with.
Regularly infusing your power into the same object will also improve them without limits, though such objects can only be used by you.
Enchanted objects will be biased towards direct combat-applicable effects, tied towards the base object. All will start with general durability, and physics immunity.
With time and use, your spiritual pool will grow, and eventually allowing you to forgo earthly needs such as eating, drinking, sleeping, breathing, and excreting waste.