Better way for Bulk Assignment of Field Level Security

Don't know of any tools that do this, but I'd do one of the following:

1. Update a single profile via the UI to match the appropriate FLS, and then update the other profiles within the force.com IDE.
   i.e. copy and paste the XML from one profile on to the others. Be careful that you don't override any other values you care about. You'd probably want to do a git diff (or similar) to double check you're only updating the appropriate parts of the code

2. Create a permission set for these fields, then apply the permission set to the appropriate users. If there are a large number of users, you can use an appexchnage product like 'The Permissioner' to assist.

If the number of profiles was smaller, I'd probably use one of the firefox extensions that lets you select an area of checkboxes to tick the correct permissions in the UI.