I wanted to grab some clarification on William's ability.

If I attack an enemy, commit an asset card to the attack and end up killing the enemy, can I then I use William's ability to put it into play?

My take is no. There are 8 steps to a skill test. In step ST.7 you would apply the results, killing the enemy. Its not until ST.8 that you discard cards committed to the skill check. As a result the cards you have committed wouldn't be in the discard pile until after the window for triggering is past.

Am I right or am I missing something?

You're right.

You can however, use the knife for it's more powerful attack, and then immediately put it back in play if the attack kills the enemy.

42 minutes ago, mwmcintyre said:

You can however, use the knife for it's more powerful attack, and then immediately put it back in play if the attack kills the enemy.

Yes because you discard it 1st. You can also do that with Lantern.

Timing is also why you cannot do that with Baseball Bat.