Focusing more on whether it would be difficult for an Engineer to become a Patent Attorney (or Agent)...
It really depends on the person. If I can generalize, let's say that there are two types of engineers.
1) the Type that can make it through the Engineering classes, but their hearts aren't completly in it- i.e., they have sufficient math and science knowledge/skills to survive in engineering, but lack the true 'geekiness' to be a successful engineer. Lack that desire to really want to know/determine how things truly work. They aren't the ones that disected VCR's, DVD players, transistor radios at a young age, or wired their sisters doll house for (DC) electricity at the age of 8, and they probably didn't own an erector set, or one of those Radio Shack experimental lab sets (and wore it out from over use). They are more rounded to both science and language-arts, and are not thrown off where 2+2 does not equal 4.
2) The type that are geek-to-the-max, that really want to know how things work and aren't afraid (and don't need to be asked) to do further study to learn more. They live and breath engineering, but usually lack somewhat on the language arts side. They built every circuit in the Radio Shack Electronic kit, along with others that they altered or devised themselves, and related to the movie "Revenge of the Nerds." And you did it because you enjoyed the journey and challenge of the build, and not necessarly the successful result. Their world crashes if there is even a suggestion that 2+2 equals something other than 4.
Regarding the Former, you would probably like patent law (prosecution), especially if you enjoy arguing, and using/manipuating words to serve your own purposes. The flux of the law, constantly changing, doesn't really bother you.
If the latter, you relish the journey of learning the new technology and really getting under it, but less so getting it down on paper. But the constant 2+2 no longer equals 4 turbulence of the law, where a single case can turn your understanding of a legal concept upside down, really bugs/disturbs you.
Either can usually survive in either Engineering or patents- the big question becomes whether you want to just 'survive' in your current engineering or patent field.
I'm glad I could completly avoid answering the question, and shed absolutely no light on the situation whatsoever- Best of Luck!