BryonD
Hero
The example provided is a table leg as a club. Seems pretty clear.Since you don't follow through with the specific language, allow me to expand.
Do you, as the DM, allow, if you judge a thing to be "close enough", just about anyone to use that thing exactly like a weapon (such as the greatclub) including proficiency bonus if proficient?
Because if so, that is the problem.
I would not allow a dead goblin to be "close enough" to a great club.
The table leg club would have the "light" quality for anyone proficient in simple weapons (or clubs).If, on the other hand, you still don't allow the proficiency bonus even when you rule the thing is close enough to the real weapon, unless the person is a tavern brawler and has the proficiency, then we're good.
As to proficiency, there is a third camp you didn't offer.
Lets say the fight is in a giant's kitchen. There is a giant's meat cleaver handy and, for sake of conversation, the DM does agree it is "close enough" to a Great Axe.
The party rogue (not proficient and no feat) grabs it and swings. It is an improvised weapon. No prof bonus, standard improvised weapon damage. (one could argue better damage for this example, but that is a completely seperate conversation). The fact that it is "close enough" to a great axe is meaningless to him.
The party wizard (not proficient, but has tavern brawler) grabs it and swings. He adds his prof bonus, but still does standard improvised weapon damage. Again, the fact that it is "close enough" is meaningless to him.
The party fighter (proficient in Great Axe, no feat) grabs it and uses profic bonus to attacks and does great axe (1d12) damage. This is because, as stated on page 147, he is proficient with Great Axe and is using a simialr weapon "as if it were that weapon".
Note that "proficient with a weapon" <> "proficient with the similar object".