Well, that is lot more complicated that it seems. There is schools saying the planet is strongest in the middle of the house, there is schools saying the planet is strongest at the cusp or begining ... This is not settled and needs more research.
However, if you have a conjunction the energies of the planets are mixed together, melted. So, it is like they both work in both houses.
I would not expect a personal planet be more in the third house or the second house, if positioned as you say. The issue with houses is there is no dominant house system. So in Placidus the cusps maybe there, in Campanus they will be at a different degree. What I want to say, that a planet around a cusp is conected to the cusp only if that is the I., IV., VII. or X. house - the axes. Because unlike all the other house cusps, these are the same in all house systems and are derived from undisputed astronomical rules.
Hope I helped
