Easy solution would be making it so guilds can't damage each other with bombs/arrow but that would be a huge problem as they would bomb/arrow spam attackers knowing they wouldn't be damaged which is OP.

There's no easy fix to the problem, but if you're a decent PKer you should be able to kill them before they get the chance too especially when there's a huge mob. You still get a decent amount of kills even when people do this, possibly make it so if one kills them selves it reduces a kill from their profile? Might make them less likely to do it I dunno.

You could use the most damage done gets the kill system but I think that would have a bigger negative affect on PK'ing than suicide, it seems like most PK'ers are more into the spamming for kills as quick as possible for the high stat.

At the end of the day I don't think it's a major problem, people still rack in thousands of kills a day there are multiple areas to PK in so if you're at Sards and really annoyed with the spike suicides just go somewhere else.