Glyph origin or Word Etymology Resources I know this topic has - kind of - been discussed over here: 
  What etymology dictionaries are available?
  


(In order to avoid seeming like I'm advertising for anyone I will refrain from mentioning where I heard this but...)

I once heard an explanation of the character 取 talking about how it came from the character 馘 (meaning: to cut off the left ear of the slain in battle) - and how the meaning of 馘 is visually represented in the character 取 (an ear + a hand) now meaning 'to take' 

Where would one go to find this type of etymological explanations?
zdic.net is an authoritative resource: http://www.zdic.net/z/16/xs/53D6.htm

会意。从又,从耳。甲骨文字形。左边是耳朵,右边是手(又),合起来表示用手割耳朵。古代作战,以割取敌人尸体首级或左耳以计数献功。本义:[捕获到野兽或战俘时]割下左耳。

However, I don't think it is true that 取 developed from 聝 and 馘, they have always been separate characters, even though Shuowen (same site) indicates that 取 has also been used in that sense: 捕取也。从又从耳。《周禮》：“獲者取左耳。”《司馬法》曰：“載獻聝。”聝者，耳也。七庾切。