You need to change the web-app version to 2.5 as previous version does not support JSP 2.1. Weblogic server enforces the jsp version mentioned in the web-app of the web.xml.
It should be like this.
<web-app xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.5" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_5.xsd">
I have uploaded a sample application which can be dowloaded from here