"Ahhhh! Firebird. One feather can light a large room. That explains it." Leslie nodded, sagely. "A very powerful core, said to be both a blessing and a bringer of ill to its owner. Which is why many wand makers are unwilling to work with it. Gregorovitch was always an innovator, in that regard, willing to experiment. I prefer to stick with what's tried and true and not dally in these more volatile cores."
They had stumbled upon Leslie's favorite topic, one which he could speak upon for hours. Simply bringing up the subject brought a sparkle to his eyes and invigorated his weary soul. It was a shame to watch the wand be concealed, but Leslie showed no judgement. After all, he was a prisoner - it would be too much to ask to weigh the wand in his hands to test its meddle.
"Working with wands as long as I have, one develops a sense for these things. A flow of energy. This flow of energy constantly surrounds and flows through us. The wand, which consists of a combination of core, wood, wood flexibility and length, focuses this energy in a useable manner, with the addition of incantations, to create different spells. Different wands have different feels, but it is so subtle that very few are able to tell the difference."
Leslie was neither boastful or proud of his ability to sense these things, but spoke plainly, as he instructed Dolohov. Even though Dolohov would usually be considered 'an enemy' by most for the fact that he was a Death Eater, Leslie remained detached enough for that not to matter.