The Wikipedia:Civility policy states the following (as of July 18, 2017):

Civility is part of Wikipedia's code of conduct and one of its five pillars. The civility policy describes the standards expected of users and provides appropriate ways of dealing with problems when they arise. Stated simply, editors should always treat each other with consideration and respect. They should focus on improving the encyclopedia while maintaining a pleasant editing environment by behaving politely, calmly and reasonably, even during heated debates.

Wikipedia's civility expectations apply to all editors during all interactions on Wikipedia, including discussions at user and article talk pages, in edit summaries and in any other discussion with or about fellow Wikipedians.

Simply being "not as mean as the next editor could be" is no excuse for being uncivil. Note that "editors should always treat each other with consideration and respect" and not "editors should almost always treat each other with consideration and respect, unless it would be really funny not to" – treat editors with respect.

While severity may come in to play for any final decision toward action against uncivil behavior, just being "less severe" does not make it okay. One editor may believe such an attack is "weak" but another may see it differently. It is best to avoid any personal attack, no matter how weak.

Even if the person doing the attack does not mean to, it can still be considered disruptive. From Wikipedia:Arbitration/Requests/Case/Portals#Good faith and disruption:

Inappropriate behaviour driven by good intentions is still inappropriate. Editors acting in good faith may still be sanctioned when their actions are disruptive.

A weak or less severe personal attack is still a personal attack. Don't do it.

• Wikipedia:Civility – policy, on comportment in discourse
• Wikipedia:Assume good faith – policy, on not projecting negative assumptions about other editors
• Wikipedia:No personal attacks – policy, taking the above ones to their logical conclusion
• Wikipedia:What Wikipedia is not – policy, including that Wikipedia is not a: debate forum, soapbox, blog, anarchy, bureaucracy, or battleground
• Wikipedia:Disruptive editing – guideline, on engaging in asinine antics
• Wikipedia:Casting aspersions – information page on how the Arbitration Committee addresses personalized denigration of other editors (hint: harshly)
• Wikipedia:Competence is required – essay bordering on a guideline; inability to get along is in fact a form of temperamental incompetence in a collaborative environment
• Wikipedia:No angry mastodons – essay, a more humorous take on hotheads
• Wikipedia:Wikipedia is not about winning – essay, on the no. 1 point most hotheads fail to grasp
• Wikipedia:There is no justice – essay, about "honor" quests that frequently get hotheaded editors into trouble
• Wikipedia:Wikipedia is not therapy – essay, about WP and people with emotional/temperament/socialization issues
• Focus on content - section of dispute resolution policy
• Category:Wikipedia essays about civility – a wealth of essays on editorial behavior, most of which are spot-on