Hey there! I recommend to read the exact descriptions of the different abilities. As far as I know, the Weighted Throwing Knife does not give back melee energy as before, but instead grants you class ability energy, so energy for your dodge. In addition to this, the Solar Aspect Knock 'em down can fully refund your Throwing Knife energy on final blows, but this only works while being Radiant. You could combine this with the Solar Fragment Ember of Torches which makes you and your allies Radiant by using powered melee attacks. This however uses your throwing knife to become radiant before you get it back, so you either need Gambler's Dodge to get a second knife or the new Acrobat's Dodge to make yourself and your allies Radiant before using your knife. Hope this helps with your build!