"Intended" vs. "intentional"

I believe the difference lies in the achievement of an objective and the motivation for it.

If I intentionally strike you in the face, I have done something deliberate and it had an effect, which was most likely to hurt and outrage you. But I could claim that my intended action was to shoo away a wasp that was about to sting you, and that striking you in the face was an unfortunate consequence (i.e., a "by-blow") of my wish to safeguard your health.

In short, the motivation for an intended act may be at odds with its consequence. An intentional act is simply one that was deliberate, saying nothing about why it happened.

An intended action is something that was desired or preferred over an alternative.

Was that your intended selection, or did you have to settle for second best.

Intended is often used to describe outcomes.

Was that the intended result, or did you hope for better?

An intentional action is one that is deliberate as opposed to random or accidental.

When you hit the lamp with the bat, was that intentional, or did you just not see it?