Many models as Two-Handed?

Since all Knight models in the RC Shop are Two-Handed, you probably can't transmute them to any knight/blade weapon since every other weapon in game is One-Handed.

The same goes to the Dota Sentinel Slayer (If I'm not mistaken)...

There are a bunch of transmute weapons in game that cannot be transmuted... so I suggest to fix it asap (even though I know Mazey won't fix soon...).

It's not about being one-handed or two-handed. It's about the job requirement. Knight weapons can be modeled with other Knight/Mercenary weapons one-handed or not. On the other hand, Mercenary weapons cannot be modeled with Knight weapons.