bonus3 bAddEle,Ele_All,x,BF_NORMAL;
This is a not so obvious but clever way to increase only normal attack damage through item bonus or player scripts. I was worried I would need to change the source since I didn't find this anywhere, so I assume not many people know about this, and felt like sharing.
I had to dig through all ideas and item bonuses to find this hidden gem. This specific use of bAddEle manages to increase all normal attack damage by X against all enemies without affecting skill damage.
Explanation: From the documentation, "bonus3 bAddEle,e,x,bf; +x% physical damage against element e with trigger criteria bf", so this was meant to increase damage against specific element enemies. This is the only damage increase with a bf criteria in rAthena's documentation, so this had to be used. So a friend and I thought of only triggering on Normal Attacks, and using Ele_All to affect all enemies, giving us the equivalent of something like a "bAddNormal" that rAthena doesn't have.