TencentTraveler is actually a legitimate UserAgent (apparently most popular browser in China), but more than likely a bot/spider/crawler is spoofing it (as well as other popular UAs). You can use htaccess if you want to block UAs or IP blocks. Someone mentioned they just all IPs from China. You may find yourself playing "whack-a-mole," but if it concerns you, you can ban IPs/UAs as you have issues.
The important thing is to make sure your site is hardened so actual malicious attacks can do no harm. I generally don't worry much about non-malicious behavior unless we're getting hammered and it effects server performance. We did get hit hard a few weeks ago from some bots, but they were attempting every known vulnerability under the sun (including many mailicious URLs). No damage done, as our sites are heavily locked down as far as security goes, but we did block the IPs because the traffic was excessive.