I was so touched [by (how this disabled man believed in people)] 主句，主系表结构。方括号里是状语；圆括号里是宾从，作介词 by 的宾语。
that I bought a toy from him (I didn't need at all) 结果状从。括号里是定从，作 a toy 的定语。

I was SO touched by how this disabled man believed in people THAT I bought a toy from from him I didn't need at all.
so ......that......如此，以至于。我如此受那个相信人的残疾人的感动，以至于从他那买了一个完全不需要的玩具。