In Nazir we discussed the issue of חרב הרי הוא כחלל and the different opinion mentioned in Tosafos there as to how strong the tu'mah is.
In our Tosafos (d.h. b'chavis) where tosafos asks that a metal kli aside from not being a valid chatzitza to block tu'mah, it should actually assist in the transfer of tu'mah because it becomes an avi avos hatu'ma like the deceased himself, and can turn the other items into an av ha'tumah. Tosafos understands that when we say חרב כחלל it is literally like the chalal and is metamei b'ohel. Rabbeinu Tam seems to assume this, which is li'shitaso with what tosafos quotes in his name in nazir. This is against the position of the ramban in chumash that חרב כחלל only applies to direct contact, not to being in the same ohel.
The Poras Yosef points out that according to the opinion of R' Chaim HaKohen in tosafos in nazir that a kohein isn't forbidden for tu'mah of חרב כחלל, there would still be a significance to the figs creating a chatzitzah between the houses despite the metal kli that assists the transfer of tu'mah. Despite the metal kli, the figs still serve as a chatzitza to make it permissible for a kohen to enter (because the חרב כחלל doesn't create an issur for kohanim), but without the chatzitza a kohen couldn't enter.