Strange result in complex limit

I'm trying to assess the limit:

``````gamma[w_] = Sqrt[-(u*e)w^2 + I*(u*s)w];
Limit[Re[gamma[x]], {x -> DirectedInfinity[1]}]
``````

I've calculated the limit by hand, and the correct answer is (I've also numerically verified some examples of $${u, e, s }$$ using the software):

$$frac s2 sqrt { frac ue}$$

But for some reason, using Limit, I get

``````{DirectedInfinity[(Sign[e]^ 2 sign[u]^ 2) ^ (1/4)]}
``````

So my questions are:

What's going on here?

What problems should I know when using Limit?