As of the June 2013 release, for security reasons Asset Bank escapes all user-entered HTML before displaying it on the page. This means that by default, any HTML that you enter will not be used by the browser to format the attribute value. Instead, the HTML tags will be displayed on the page e.g: <em>Lorem <b>Ipsum</b></em>.
If you wish to use HTML in your attribute values, you will need to edit the attribute in question and ensure that the 'Edit/Show as HTML' box is ticked (screenshot below). Please note that HTML formatting is only supported for attributes of type 'Text area' and 'Text area (long)'.