> I want a fire source that is eternal.

Try a large magnifying glass, or a focussing mirror.

Otherwise anything you use is going to wear out eventually. For the long run you need to learn how to make a new one yourself. In practice that probably does mean a fire-bow. Flint rocks are common in some areas and can be used to make a spark.

Personally I go with a flint-ignition cigarette lighter. When it has fuel it's easy to use one-handed and doesn't need special tinder. When the fuel runs out, the spark will still ignite tinder that is well-prepared. The flint will wear down eventually, but spare flints are small and cheap and easy to stock-pile.

> The fire piston. ...It also can lose its seal which is needed for it to work.

Yep. Mine seems to need a continuous supply of vasaline to keep it going.