So, Google has failed me and I turn to you.

Were there any common practices during thunderstorms to put away/lay down sheathed swords? I'm looking particularly at the 14th century, although sources on carrying swords from any period would help.

looking forward to answers.

I've never heard of such. Why would there be?

If the concern is being zapped by lightning, I suspect a pointy helmet (or spear, pike, halberd, poll-axe etc) would pose a similar risk as a sword. My guess is that people avoided fighting in thunderstorms because of the rain more than any risk from lightning. Aside from it being miserable, the mud would make it risky for cavalry and dismounted knights and make troop coordination difficult due to poor visibility.

Although I could be missing the point of your question.

Did people of that era even know that lightning is attracted to tall, conductive objects? I suspect not, since people were only just getting the idea in the eighteenth century. Ben Franklin is credited with the first lightning rod in 1749.

Then again, there may have been a common knowledge, but not a scientific one.

Sorry, I don't know the answer to your question but this thread might interest you:

http://myArmoury.com/talk/viewtopic.php?t=30411