Differences between 2.10 and 2.5

1. In 2.10, the Fire Boomerang will stun enemies like Darknuts, Wizzrobes, Peahats, and Pols Voices, but these enemies are not damaged by the boomerang or its damaging sparkle, even though they still flash. In 2.5, however, the fire boomerang's damaging sparkle actually damages these enemies, and can kill them after a few hits.
2. In 2.10, the hookshot's chain can actually damage enemies like Darknuts, Wizzrobes, Peahats, and Pols Voices. In 2.5, however, the hookshot chain can no longer damage these enemies.

In my post 2.5 ideas diary, I mentioned some defenses for Arrow Sparkles, Boomerang Sparkles, Hookshot Chains, and all sorts of other weapons.

Perhaps you should report these as bugs.