I can't explain all of them since I'm not much of an Assassin player but I can tell you what the "Master's Runic Talons of Quickness" are about:
Basically a Bearsin needs 100% IAS on her weapon to reach 3FPA standard attack and in order to achieve this you need a Claw with 3os and 40% IAS. Now you can get an "Artisan's Runic Talons of Quickness" in 1.14d but the chances are very low to get the sockets and you have 0% chance of a useful prefix. By comparison in 1.10a you have a 4/6 chance of getting 3os and a 1 in 67 chance for 40% IAS. So that's about a 1 in 100 chance for 100% IAS claws.
And then you can get a useful Prefix on top, which max definitely did.